If you think I wouldn't shoot, you're a fool. Now I'll wire one of your wrists to mine; we've got a long march ahead."

So, when these meanings became clear in his mind, he wrestled Brinker at every turn. Twice he almost won. He argued and cursed, getting nowhere. He defied Brinker to shoot him. The big man didn't do that. But at last Brinker jabbed a hypodermic needle—part of the regulation medical kit—through the flexible rubberized fabric of the elbow-joint of Copeland's spacesuit, and into his arm.

Many hours later, and many miles farther into the mountainous country, Copeland awoke in a cavern with glassy walls, illuminated by Brinker's ato-light. Brinker stood near where he lay. He seemed just grimly good-humored.

"This is an old Martian supply depot, Cope," he offered. "I found it before I knew you, and I kept it in reserve for possible trouble, like now. I knew I could convert its contents to considerable money at any time. So it was like a bank-account, and a last resort, too. There's even a small Martian spaceship; only three others have ever been found, intact. I also cached some Earthly instruments here. You can bet I didn't leave any tracks for miles around."

Copeland's gaze caught the errie gleam of the strange little craft. He saw the stacks of oddly-made boxes and bales. His hackles rose as he thought of a senseless plunge into unplumbed distance.

"Unwire my hands, Jess!" he coaxed again, trying to control fury. "Get wise! Damn you—you're more dangerous as an altruist than any crook could be!"

Brinker's laugh was sharp, but his eyes held real apology. "Want to help me ready and load the ship?" he said almost mildly. "No—I guess not; you aren't quite in a cooperative frame of mind, yet. I'll need you later. Sorry, but you're the only guy around, Cope."

Brinker blasted queer bulkheads out of the ship, in order to make it habitable for humans. The exit of the cavern had been masked with debris, but now he cleared it. He tossed Copeland aboard and took off into the lunar night.

Hurtling outward, they passed the orbits of Mars, the asteroids, Jupiter, and Saturn. There, with Earth-made instruments, Brinker located what he sought: Brulow's Comet.

So far from the sun, where the fluorescence-inducing radiations were thinned almost to nothing, it glowed hardly at all. And it had almost no tail; it was only a gigantic, tenuous ghost, with a core of stone and magnetic iron fragments.

Still dazed, Copeland thought about comets. Wanderers, following elongated orbits that loop tight around the sun at one end and plumb the depths of space at the other. Of all large forms moving through the void, they were the least dense. In coma and tail, they were only intensely rarefied and electrified gas. The great enigma about them was that things so deficient in mass and gravity could hold onto even that much atmosphere for long. Perhaps new gases were baked out of the meteoric core, each time a comet was close to the sun; maybe some of them even renewed their atmosphere periodically, by capturing a little of the tenuous substance of the solar corona, during their very near approaches to it.

Brulow's Comet was on the sunward swing, now, gaining speed under solar gravitation; but it still had a long ways to go. Brinker guided the ship down through its coma and toward its lazily-rotating nucleus, where thousands of fragments of iron and rock swirled around their common center of gravity.

The chunks clattered against the craft's metal hull, but did no damage at their low speed. Brinker brought the ship to rest at the center of the nucleus, where there was one solid mass of material a hundred yards in diameter.

"Well, we're here, Cope," Brinker said grimly. "We don't have to work right away—if you don't want to. We've got too much time."

Those two years looming ahead were the worst. If the Moon had been harsh, it was nothing to this eerie place. The heart of this small comet was illumined by faint, shifting phosphorescence, ranging from blue and tarnished silver to delicate if poisonous pink. Perhaps the cause was the same as that of the terrestrial aurora. The silence here was that of space; but the swirling motion of the nucleus suggested a continuous maddening rustle to Copeland.

He had to yield to Brinker's wishes. Toil might divert him some, keep him from feeling the tension of time and strangeness so much.

"Okay, Brinker," he said. "You win. Brulow's Comet is headed for a close approach to the Earth-Moon system. So you want to be spectacular, and shift it a little from its orbit—so that it will hit the Moon and maybe break its crust. Was that so hard to figure? That sounds pretty big, doesn't it? But I'll humor you. Let's see how far we get ... Since we're here." His sarcasm was tired.

As a preliminary, they cut a cavern in the central mass of the nucleus with Martian blasters, and fitted it with a crude airlock. The cavern would be better to live in than the interior of a ship meant for alien beings. They moved Martian apparatus and supplies into it: Air-rejuvenators, moisture-reclaimers, cylinders of oxygen and water, and containers of nourishment—all millions of years old.

Their remaining supply of Earthly food in their packs was now very short. It was weird—eating what had been preserved so long ago, on another world, for beings just barely close enough to human for their food to be edible. Gelatins, sectional fragments of vegetation, and what might have been muscle-tissue. Copeland and Brinker both gagged often. It wasn't the bland, oily taste so much, but the idea....

Some of it, Copeland decided, was not native Martian. It was more like terrestrial fish. And slabs of coarse meat might have been flesh of the last dinosaurs! Martians surely must have visited Earth briefly, though evidence there had long since weathered away.

Whenever, in the slow swirling of the nucleus, tubes pointed in the calculated proper direction at right angles to the comet's course, they were fired in long bursts. Thus, slowly, like a perfectly-balanced bank vault door moved by a finger, the mass of the comet—slight by volume, but still measuring many thousands of tons—was deflected in the opposite direction. Astrogation-instruments showed the shift. Copeland had expected such coarse deflection to be possible; still, it startled him—this was the moving of a celestial body!

"Just a little—for now, Cope," Brinker said. "We'll leave the fine aiming for