by Hal Clement
He would have to be sure that he let the planet’s air only into chambers where it could not reach either his own tissues or the ship’s circuitry. No, wait. The test should take only minutes or hours, not years. Both his flesh and the silver wires could stand oxygen that long, and he could get rid of it later by opening the hull to the vacuum of space. That made matters easier—much easier.
But how could he detect the change in pressure, if it did occur? He did have manometers, of course. But they were vented to the outside of his hull. No one had foreseen a need for measuring internal pressure. He would have to do some more hard thinking.
What effects would pressure produce, besides merely mechanical ones? There would not be enough change, in the electrical properties of the exposed wires, for even the agent to detect. The change would probably not be fast enough to alter the temperature noticeably. And even if it did alter it, he would not be able to tell whether the change were due to gas laws, or simply the operation of the machine.
In the temperature range of this world, it was not really certain that all the products were gaseous, anyway. The mere fact that he had detected them in that form, during his approach, meant nothing. The infra-red spectrographic equipment he had used would have picked up trace quantities. It was unfortunate that its receivers were also aimed outward.
The agent could not, for the life of him, recall the vapor-pressure curves of any of the expected products—though, come to think of it, something was liquid here. The clouds he could see proved that, as did their precipitation on his half. He could not assume that it was one of the products he sought, however, and his best bet was still to maintain pressure change. If he could do it . . .
As usual, the solution was ridiculously simple, once the traveler had thought of it. Most of the access-doors in the hull opened outward and all were operated electrically. He had perfect control over the current supplied to their operating motors. He knew that if he refrained from latching one or more of the doors, and simply held it shut with the motor, he could sense directly the amount of effort needed to keep it sealed against the internal pressure.
As far as he was concerned, it was a quantitative solution—if the pressure increased. If it decreased—well, he would know it, from the extra effort needed to open the door. He was concentrating on immediate small details now—and very wisely.
With his machine, action could follow thought without delay. The moment he had his answer, a door swung open in the side of the great metal egg he was driving, and Earth’s air poured in. Good as his seals were, the ship had not, of course, retained any significant amount of gas in the millennia it had been in space.
He did not bother to develop a plan for enticing one of the machines through the opening. He assumed, quite justly, that any intelligent mind must have a fair proportion of curiosity in its make-up. The fact that sell preservation might oppose this influence did not, as far as the agent knew or suspected, apply to the present situation. The risk of sacrificing even an expensive remote-controlled machine should be well worth taking in such circumstances. He simply waited for one of the devices to be driven into his ship.
Before this happened, however, there was a good deal of conversation among the machines present and, he presumed, the distant broadcaster—if, of course, it could be called conversation. The agent was still unable to reconcile this supposition with the absence of intelligent life in the present group.
At last, however, the expected event occurred. One of the machines swung about and moved toward the opening in the hull. Just outside, it halted, and the agent guessed at a brief burst of atmospheric pressure waves, though his manometers did not react fast enough to catch them. Then it entered.
It traveled on four struts instead of two. It became completely horizontal and advanced on the supporting struts. Evidently the upper ones, which the agent had seen, could be used for locomotion when desirable. Its entrance was slower than by its usual rate of motion, though the agent could not imagine why. The suggestion that slower motion made detail observation easier would never have occurred to a being whose perception and recording operations occupied fractions of a microsecond. Whatever the reason for the delay, it finally managed to get inside.
The agent wasted no time. Ready to observe anything and everything that resulted, he shut the access hatch. Results, by his reaction-time standards, were slow—additional evidence that remote control was involved. The electromagnetic unit burst into activity the instant things finally began to happen. Some of the machines outside began to tap on the hull with dimly perceptible solid fragments, apparently pieces of silicate rock. The agent tried to find regularities in the blows that might be interpreted as communication code of some sort. He failed.
One of the devices, standing a little distance away, moved one of its attached fragments of metal until a hollow cylinder—which formed part of it—was in line with the hull. After a long moment the more distant end of the cylinder filled with gas, sufficiently ionized to be clearly perceptible to the alien.
The gas must have been under considerable pressure, for almost instantly it began to expand, driving before it a smaller fragment of metal which had plugged the tube. This fragment became progressively easier to perceive as its speed through the planet’s magnetic field increased.
It emerged from the near end of the cylinder with sufficient momentum to continue in a nearly linear course, until it made contact with the hull. The agent watched with mounting excitement as it flattened, spread out and finally broke into many pieces. Incredible! He analyzed it, both electrically and mechanically, from the way it broke up. But he could make no sense of the operation.
After a time, the pounding ceased, and the two machines remaining outside drew together. No obvious activity came from them for some time.
Inside the hull, more interesting, possibly more understandable, events were taking place. The moment the door had closed, the machine trapped within had attempted to withdraw. Its action was a trifle faster than that of the ones still outside. The agent could not decide whether this meant that the escape reaction was automatic or that a distant controller had turned his attention to the captive machine first.
It had pounded aggressively on the inside of the door in the same seemingly planless fashion as its fellows. Then it had slowed down, and began to move another of the strangely fashioned pieces of metal distributed about its frame. This abruptly became clearly perceptible, as an electric current began to flow through portions of its structure.
The source of the current was a seemingly endless supply of metallic ions—quite evidently chemical energy could be used for something. The current’s function was less obvious, since it was led through a conductor whose greatest resistance was concentrated in a tight metal spiral.
This must in some way have been shielded from atmospheric oxygen, at fairly high temperature if the ion cloud around it meant anything; it nevertheless remained uncorroded. Heating the wire seemed all that the device accomplished—the agent refused to believe that the ion cloud was intense enough to help either in action or perception. The light and heat radiated were inconsiderable, but—wait! Perhaps that was it—perhaps this machine had eyes!
The agent examined the electrical device more closely, and discovered that part of its uncharged structure consisted of a roughly paraboloidal piece of metal, which must certainly have been able to focus light into a beam, of sorts.
A few moments later, it became evident that it did just that. The agent’s body was exposed in several places in this part of the ship, and, time after time, one part would be struck by radiance, while the rest were in more or less complete darkness. Furthermore, a few minutes’ observation showed that when the machine moved at all it followed the direction in which the light beam happened to be pointing at the time.
Sometimes it did not move, though the beam kept roving around the chamber. The agent deduced from that one of two things. Either the device had several eyes, or the one it had was movable over v
irtually the entire sphere of possible directions. The thing was making an orderly survey of the interior of the space in which it was trapped. But it was carefully refraining from touching anything except the floor on which it stood.
That portions of this floor consisted of the agent’s tissue made no difference to either party—as far as either knew. But the agent began to wonder how much of the exposed machinery of the ship would be comprehensible to the presumed distant observer.
Still more, he wondered how this presumed observer maintained contact with his machine. There was no energy whatever—in any form that the agent could detect—getting through his hull, either to or from the trapped machine. A minor exception to this might be the pressure waves generated by the stones striking his hull. But he had already failed to find in these blows any pattern at all, much less one which could be correlated with the actions of the machine inside.
Naturally, the thought that this might be an automatic device, similar to the mole robots, could hardly help occurring to the Conservationist. If this were the case, its present behavior was far more complicated than that of any such machine he had ever encountered. But hold on—he had already faced the implications inherent in that idea. So the technology of this world was more advanced, in some ways, than his own. There were still things the natives didn’t know—things which would most certainly hurt them. Any concern he might have felt about himself was drowned in this larger solicitude.
He wondered whether he could so operate any of his own machinery to or through his prisoner, so as to convey a message of any sort. Certainly, if it used light as a vehicle of perception, it could detect motion on the part of the relays. For example—they were larger by quite a margin than the wave length of the radiation the hot wire was emitting in greatest strength.
There were several hundred thousand of them in the dozen square yards exposed to the direct-line vision of the captive, which should be enough to form some sort of pattern. Some sort of pattern, that is, if their owner could figure out how to operate them without making the ship misbehave.
He was still pondering this problem, along with the question of just what would be a meaningful pattern to the operators of the machine, when his attention was once more drawn to the outside.
The machines there seemed to have taken up a definite course of action. They had once more approached the hull, and were doing something to it which he could not at first quite understand. It quickly enough became evident, however. The brightness of the images he was receiving through the eyes, to which he had naturally been paying very little attention, began rapidly to decrease. Within a minute or so, the lenses ceased to transmit at all.
His tactile “sense” consisted in part of the ability to analyze the response of his hull to the vibrating impulses he applied to it. If such impulses were followed faithfully he could be sure that there was no mass in contact with the surface. On the other hand, if they were damped to any extent, he could form a fairly accurate idea of the amount and even some of the physical properties of such a mass.
In the present case, he discovered almost instantly that his eye lenses had been covered with a most peculiar substance. It not only adhered tenaciously to them, but seemed to absorb without noticeable reaction the same vibrations which had sent the soil dancing out of his way like summer chaff in a breeze. This did not particularly bother him, since the eyes were nearly useless for watching the machines anyway. But he kept trying to shake the material off, while he considered the implications of the move.
One was that the machines depended, far more heavily than he had suspected, on the sense of sight, and must suppose that he did likewise. Another was that they were about to take measures which they did not want observed by him. He did not worry seriously about anything they could do to his ship, but he began to listen very carefully for their footsteps all the same.
Another possibility was that they simply did not want him to fly away with the captive machine. To a race dependent upon sight, no doubt the idea of flying without it was unthinkable. He wondered, fleetingly, whether he should move a few hundred yards, just to see what effect the act had on them. Then the actions they were already performing caught his attention, and he shelved the notion. He became alarmed at what appeared to be an abrupt change of plan.
Two of the things were leaving the neighborhood, in a direction more or less toward the other electromagnetic radiator. Making allowances for the difficulty these machines apparently suffered in traveling over uneven terrain, the agent felt reasonably sure that this was their goal. The other two remained near him and settled down to relative motionlessness, as nearly as he could tell. He comforted himself with the thought that whatever plan they were attempting might demand some time to mature.
Perhaps the departing machines were going after additional equipment, though it appeared their goal might be attained more rapidly by sending other machines from the control point. However, it was quite possible that no others were available—such was likely enough to be the case on any of his own worlds, where only one individual in five hundred was machine-equipped, and over half of these were incapable of locomotion. Pride swelled in him at the thought, but he dismissed it as unworthy.
His soliloquy was interrupted by something that had not happened to him since his ship had first lifted from the world on which it had been built. The incident itself was minor, but its implications were not. The hull vibration, which he was still applying near all of his aboveground eyes, stopped near one of them.
He had not stopped it. The command for the carefully planned motion pattern was still flowing along his nerves. It should have been inducing the appropriate response in a fairly large group of relays. Something had gone wrong, and it produced a sudden crisis in his thinking.
The ship, of course, was equipped with a fantastic number of test-circuits, and he began to use them for all they were worth. It took him about three milliseconds to learn a significant fact. All the inoperative relays were close to, or actually within, the compartment where the captive machine was located. Closer checking showed that the trouble was mechanical—the tiny switches were being held in whatever position they had been in when the trouble struck.
Worse, the paralysis was spreading. It was spreading with a terrifying rapidity. The basic cause was not hard to guess, even with the details far from obvious. The agent instantly unsealed the door barring his captive from the outside world, and felt thankful that the controls involved still functioned.
The thing lost no time in getting out, and the pilot lost even less in getting the door securely sealed after it. For the time being, he completely ignored what went on outside, while he strove to remedy the weird disability. He was far from consoled by the thought, when it struck him, that he had proved what he wanted to know.
Something solid had blocked the relays—had, more accurately, formed around their microscopic moving parts. Whatever it was must have come in gas form for he would have felt the localized weight of a liquid, even inside. Most of the interior of his ship, as well as his own flesh, was still far colder than the planet on which he was lying.
Quite evidently one of the exhaust products of the captive machine, released as a gas, had frozen wherever it touched a cold surface. It might have been either water or one of the oxides of carbon. The agent neither knew nor cared. He proceeded to run as much current as possible through all his test-circuits, with the object of creating enough resistance-heat to evaporate the material.
The process took long enough to make him doubt seriously that his conclusion could be correct. But eventually the frozen relays began to come back into service. He could have speeded up the process, by going up a few miles and exposing his interior to the lowered pressure, and he knew enough physics to be aware of the fact.
It spoke strongly for the shock he had received that he never thought of this until evaporation was nearly complete. It was lucky for his peace of mind that he never realized what the liquid water formed in the process mi
ght have done to his circuits. Fortunately, formed as it had been, it contained virtually no dissolved electrolytes and caused no shorts.
He realized, suddenly, that he had permitted his attention to stray from the doings of the nearby machines for what might be an unwise length of time, and at once resumed his listening. Apparently, they were still doing nothing. No seismic impulses were originating in the area where he had last perceived them. That eased his mind a trifle, and he returned to the problem of the material covering his eyes.
This stuff seemed to be changing slightly in its properties. Its elasticity was increasing, for one thing, and the change seemed to be taking place more rapidly on the side from which the air currents were coming. The agent could think of no explanation for this. He tried differing vibration patterns on the stuff, manipulating them with the skill of an artist—but a long time passed before he had anything approaching success.
At last, however, a minute flake of the material cracked free and fell away—and he could really see! He could actually make out what was going on!
V
The reason was obvious, of course. With an aperture of thirty centimeters and a focal length of about twenty-seven, the focus of the Conservationist’s eye-lenses was highly critical; with the aperture about half a millimeter, as it had been left by the fragment of clay he had broken off, it became a minor matter.
He recognized the machines easily, near the edge of his new field of view, and began to work on the covering of a better-located eye. He did not succeed quite so well here, as the fragment he finally detached was larger, and the image correspondingly less clear, but it was still a good-enough job to enable him to follow the actions of the devices visually.
