Split Infinity

Neysa plunged into a thicket. The saplings brushed close on either side, impossible to avoid—but they bent aside when pushed, and could not sweep off a firmly anchored rider who was prepared. She shot under a large horizontal branch, stout enough to remove him—but again he slid around to the side of her body, avoiding it, and sprang to her back when the hazard was past. Real riding was not merely a matter of hanging on; it required positive anticipations and countermoves to each equine effort. He could go anywhere she could go!

Neysa charged directly toward the next large tree, then planted her forefeet, lifted her rear feet, and did a front-foot-stand that sent her back smashing into the trunk. Had he stayed on her, he would have been crushed gruesomely. No game, this! But Stile, now wise in the ways of unicorns, had dropped off as her motion started. He had less mass than she, weighing about an eighth as much, and could maneuver more rapidly when he had to. As her rear feet came back to the ground. Stile’s rear feet came back to her back, and his hands resumed their clutch on her mane.

She snorted again. Round three was over. Round four was coming up. How many more tricks did this phenomenal animal have? Stile was in one sense enjoying this challenge, but in another sense he was afraid.  This was no Proton Game, where the loser suffered no more than loss of status; this was his life on the line.  The first trick he missed would be the last.

Neysa came onto a grassy plain. Now she accelerated. What was she up to this time? It didn’t seem so bad—and that made him nervous. Beginning with a walk, she accelerated to a slow trot. The speed differential was not great, as a slow trot could be slower than a brisk walk. In fact. Stile had worked with lazy horses who could trot one meter per second, rather than the normal three or four meters per second. The distinguishing mark was the beat and pattern. In walking, the horse put down the four feet in order, left-front, right-rear, right-front, left-rear, four beats per cycle. Trotting was two-beat: left-front and right-rear together, followed by right-front and left-rear together. Or with a right lead instead of a left. The point was that the motion of each front foot was synchronous with one hind foot; in some cases the front and rear moved together on the same side. But there were only two beats per cycle, the pairs of feet striking the ground cleanly together. It made for a bumpy but regular ride that covered the ground well, and looked very pretty from the side. A slow trot could be gentle; a fast one could be like a jackhammer. But a trot was definitely a trot, at any speed; there was no mistaking it. Stile liked trot-ting, but distrusted this one. He knew he had not seen the last of this mare’s devices.

Next she broke into a canter: three-beat. Left-front, then right-front and left-rear together, and finally right-rear. Like a cross between a walk and a trot, and the ride a kind of gentle swooping. All perfectly conventional, and therefore not to be trusted. She had some-thing horrendous in her canny equine mind!

Finally she reached a full gallop: a modified two-beat cycle, the two front legs striking almost but not quite together, then the rear two. A four-beat cycle, technically, but not uniform. Beat-beat, beat-beat, at the velocity of racing. Stile enjoyed it; he experienced an exhilaration of speed that was special on a horse—unicorn. Motored wheels could go much faster, of course, but it wasn’t the same. Here, as it were in the top gear, the animal straining to the limit—though this one was not straining, but loafing at a velocity that would have had another one straining—

The unicorn shifted into another gait. It was a five-beat—

Stile was so surprised he almost dropped off. No horse had a five-beat gait! There were only four feet!

No horse—there he was again. He kept forgetting and getting reminded in awkward ways. This gait was awful; he had never before experienced it, and could not accommodate it. BEAT-beat-BEAT-BEAT-beat, and over again, bouncing him in a growing resonance, causing him to lose not his grip but his composure. He felt like a novice again, fouling himself up, his efforts to compensate for the animal’s motions only making it worse. As a harmonic vibration could shake apart a building, this fifth-beat was destroying him. He would fall—and at this breakneck velocity he could . . . break his neck.

Think, Stile, think! he told himself desperately.

Analyze: What is the key to this gait?

His hands were hurting as his clutch on the unicorn’s mane slowly slipped. His thigh muscles were beginning to cramp. Stile was expert—but this creature had his number now. Unless he could get her number too, soon.

Four feet, five beats. One foot had to repeat. Number the steps: one-two-three-four—where was the repeat?  Fingers slipping...