The sub made another approach, similar to the preceding two, and I tried to line up for another kick. My friend, however, had different ideas. He was much farther from the center than I was, and could exert much more torque. He could also see where the legs were, and when I shifted my weight to line up the proper one with the approaching grapple he interfered. He was too smart to fight me directly,

though he probably could have managed it; instead, he let me get moving and then supplied an extra shove to one side so that I either overshot or missed the right position. I made three attempts to line up as the hand was coming in and finally gave the kick a little out of line when the sub was about to make contact. The leg grazed the side of the handler and put a little spin on the tank, but didn’t hit anything solid enough to push us apart. Worse, it gave the sub operator a chance to grab the leg itself. This he seemed to feel was a better hold than whatever he had planned on; he clamped on tightly and began to cut buoyancy once more.

This proved to be a mistake, though it didn’t help me as much as it might have. The leg wasn’t strong enough to hold the tank down. It parted, and once more the sub disappeared below me. I cut my lights promptly, hoping that my passenger had lost his hold with the jerk. Maybe he did, but if so he wasn’t far enough away to lose track of me. In a few seconds the tapping resumed, and in a few more the lights of the sub were close enough to make my blackout an idle gesture. I turned mine back on again so that I could see to resume the sparring match.

Now he got the idea of making his approach toward the spot where the leg had been lost, so that I’d have to turn further to bring another into line. My swimming friend was co-operating nobly, and for a little while I was afraid they had me. The sub operator was too smart to try for a leg again, but he managed to keep out of the way of several kicks I gave out. He got in, made what should have been a successful grab at something on my outer surface, but was hurried and missed. He had to back up for another try. . and I had time to get another idea into operation.

I knew where the swimmer was. I could see enough of him to tell not only that but to guess which way he’d be pushing next time. I began to put a spin on the tank with him at one pole so that he wouldn’t notice it quite so quickly. This worked, though I didn’t get a really rapid rotation — I couldn’t, of course, with such poor torque; but with the tank’s weight I had enough for what I wanted. One of my strong points in basic physics, ages ago in school, was mechanics. I couldn’t handle the present problem quantitatively because I didn’t know either my angular speed or the tank’s moment of inertia, but I hit the qualitative answer on the button. As the grapple approached again I shifted my weight to start the tank processing. Billy Barnacle tried his usual stunt of pushing me sideways and sent the leg right through the point I wanted. Either he’d forgotten what they’d taught him about gyroscopes or he was getting tired. I hit the grapple dead center with my kick, and we were apart again. If I’d been driving that sub, I’d have been getting tired of the whole business by now.

Apparently he was more patient than I. He was back again all too soon.

I had gained maybe three or four hundred feet with each pass of our duel. I had an uneasy feeling that I was going to run out of tricks before those increments added up to the total distance to the surface. Certainly if he had the patience to keep repeating the same technique, he’d soon run me dry.

He didn’t, though. He seemed to have decided that the grapple wasn’t quite the right tool after all. When he came back next time he did his usual speed-matching some distance above me, instead of level. A small light flickered, apparently in code, and my pressure-proof friend let go of the tank and swam up to the sub. He was back in a moment, trailing a line behind him.

Apparently it had been decided that human hands were more versatile than mechanical ones.

At first I wasn’t worried. There was nothing on the outside of the tank except the legs which would really lend itself to the attachment of a rope, and it had already been demonstrated that the legs weren’t strong enough. Hours before, on the bottom — no, come to think of it, it was much less than one hour — my pal had felt the need of a cargo net to wrap around the sphere. If he didn’t have such a net here, all should be well.

He did, unfortunately. It was bigger and heavier than the one they had had on the bottom, which was probably why he wasn’t swimming with it. When he got back just above the tank he began hauling on his line, and the net emerged from one of the sub’s service ports. He pulled it to him and began to spread it out so that my tank would float up into it. He failed the first time through no doing of mine; he simply didn’t get his net deployed in time. I ran into it while it was still only partly open. It had more of its weight on one side of me than on the other, so I automatically rolled out from under it and kept on rising. I didn’t have to move a finger. The sub was also rising, of course, so the net trailed downward to the end of its line and folded itself together. The boy in the sub had to reel in mechanically while the swimmer held onto me, before they could go through it all again.

That was another few hundred feet gained.

The next time they spread the net much farther above me. Once open it was even less maneuverable than the tank, and by a little judicious rolling to make the outer irregularities affect my direction of ascent I managed to get far enough from its center to roll out the same way as before. What that team needed was two more swimmers, I decided.

It turned out that one more was enough. They reeled in the net again, lifted the sub a distance, adjusted its buoyancy so that it rose a little more slowly than I did, and then the operator came out to join the swimmer. Each took a corner of the net and with the boat for the third corner formed a wide triangle which they were able to keep centered over me. I tried to work toward the sub, which seemed to be unoccupied and wouldn’t back up to keep the net spread. It didn’t work. The men moved just a little in the same direction, letting the net sag toward me.

The next thing I knew it was draped around me, and I couldn’t tell which way to roll even if I had been able to start rolling. The swimmers came in from their corners and began tying it together at the bottom.

If they finished, I was done. I watched them as well as I could, trying to spot where there was an edge — anything to tell me that there was more weight of net on one side of me than the other. I spotted what I thought was a chance to interrupt the work while I got a better look, and I’m afraid I took it.

One of the men was next to the tank and a little below it, pulling a section of net closer. Maybe it was the sub operator — the light was good, but I didn’t take time to check — and he wasn’t as familiar with the leg arrangement as his companion. Anyway, he was in the way of one of them, and I let him have it.

My intention, if I had one — I really didn’t take time to think — was to knock him out of the way so I’d have a chance to roll out of the net. I certainly didn’t mean to do him serious or permanent damage. The disk at the end of the leg, though, caught him on the right side and could hardly have helped breaking some ribs. It kicked him away like a shark butted by a dolphin. The line he was holding practically flew out of his right hand, and a tool whose nature I couldn’t make out fell from his left. He began to sink out of sight.

The other swimmer was onto him before he’d left the reach of the lights. He was evidently out cold; his body was completely limp as his friend towed him up toward the sub. I didn’t watch too closely, partly because I was trying to roll myself out of the net and partly because I regretted what I’d done.