Flesh and blood have their limits as far as speed is concerned, but Lackland came very close to setting new ones. He did not stop to solve any differential equations which would tell him the rock’s time of arrival; he threw power into the motors, turned the tank ninety degrees in a distance that threatened to twist off one of its treads, and got out from the mouth of the channel which was guiding the huge projectile toward him. Only then did he really come to appreciate the architecture of the city. The channels did not come straight into the open space, as he had noticed; instead, they were so arranged that at least two could guide a rock across any portion of the plaza. His action was sufficient to dodge the first, but it had been forseen; and more rocks were already on their way. For a moment he looked around in all directions, in a futile search for a position which was not about to be traversed by one of the terrible projectiles; then he deliberately swung the nose of the tank into one of the channels and started uphill. There was a boulder descending this one too; a boulder which to Barlennan seemed the biggest of the lot — and to be growing bigger each second. The Mesklinite gathered himself for a leap, wondering if the Flyer had lost his senses; then a roar that outdid anything his own vocal apparatus could produce sounded beside him. If his nervous system had reacted like that of most Earthly animals he would have landed halfway up the hill. The startled reaction of his race, however, was to freeze motionless, so for the next few seconds it would have taken heavy machinery to get him off the tank roof. Four hundred yards away, fifty yards ahead of the plunging rock, a section of the channel erupted into flame and dust — the fuses on Lackland’s shells were sensitive enough to react instantly even to such grazing impact. An instant later the rock hurtled into the dust cloud, and the quick-firer roared again, this time emitting half a dozen barks that blended almost indistinguishably with each other. A fair half of the boulder emerged from the dust cloud, no longer even roughly spherical. The energy of the shells had stopped it almost completely; friction took care of the rest long before it reached the tank. It now had too many flat and concave surfaces to roll very well.

There were other boulders in position to roll down this channel, but they did not come. Apparently the giants were able to analyze a new situation with fair speed, and realized that this method was not going to destroy — the tank. Lackland had no means of knowing what else they might do, but the most obvious possibility was a direct personal attack. They could certainly, or almost certainly, get to the top of the tank as easily as Barlennan and repossess everything they had sold as well as the radio; it was hard to see how the sailors were to stop them. He put this thought to Barlennan.

“They may try that, indeed,” was the answer. “However, if they try to climb up we can strike down at them; if they jump we have our clubs, and I do not see how anyone can dodge a blow while sailing through the air.”

“But how can you hold off alone an attack from several directions at once?”

“I am not alone.” Once again came the pincer gesture that was the Mesklinite equivalent of a smile.

Lackland could see the roof of his tank only by sticking his head up into a tiny, transparent view dome, and he could not do this with the helmet of his armor on. Consequently he had not seen the results of the brief “battle” as they applied to the sailors who had accompanied him into the city.

These unfortunates had been faced with a situation as shocking as had their captain when he first found himself on the roof of the tank. They had seen objects — heavy objects actually falling on them, while they themselves were trapped in an area surrounded by vertical walls. To climb was unthinkable, though the sucker-feet which served them so well in Mesklin’s hurricanes would have served as adequately in this task; to jump as they had now seen their captain do several times was almost as bad — perhaps worse. It was not, however, physically impossible; and when minds fail, bodies are apt to take over. Every sailor but two jumped; one of the two exceptions climbed — rapidly and well — up the wall of a “house.” The other was Hars, who had first seen the danger. Perhaps his superior physical strength made him slower than the others to panic; perhaps he had more than the normal horror of height. Whatever the reason, he was still on the ground when a rock the size of a basketball and almost as perfectly round passed over the spot he was occupying. For practical purposes, it might as well be considered to have struck an equivalent volume of live rubber; the protective “shell” of the Mesklinites was of a material chemically and physically analogous to the chitin of Earthly insects, and had a toughness and elasticity commensurate with the general qualities of Mesklinite life. The rock bounded twenty-five feet into the air against three gravities, hurtling entirely over the wall which would normally have brought it to a stop, struck at an angle the wall of the channel on the other side, rebounded, and went clattering from wall to wall up the new channel until its energy was expended. By the time it had returned, in more leisurely fashion, to the open space the main action was over; Hars was the only sailor still in the plaza. The rest had brought some degree of control into their originally frantic jumps and had either already reached the top of the tank beside their captain or were rapidly getting there; even the climber had changed his method of travel to the more rapid leaping.

Hars, unbelievably tough as he was by terrestrial standards, could not take the sort of punishment he had just received completely without injury. He did not have his breath knocked out, since he lacked lungs, but he was scraped, bruised, and dazed by the impact. Fully a minute passed before he could control his motions sufficiently to make a coordinated attempt to follow the tank; why he was not attacked during that minute neither Lackland, Barlennan, nor Hars himself was ever able to explain satisfactorily. The Earthman thought that the fact that he was able to move at all after such a blow had frightened any such thoughts out of the minds of the city dwellers; Barlennan, with a more accurate idea of Mesklinite physique, thought that they were more interested in stealing than in killing and simply saw no advantage in attacking the lone sailor. Whatever the reason, Hars was permitted to regain his senses in his own time and, eventually, to regain the company of his fellows. Lackland, finally brought up to date on just what had happened, waited for him; when he finally reached the vehicle two of the crew had to descend and practically throw him to the roof, where the rest promptly undertook first-aid measures.

With all his passengers safely aboard, some of them crowded so close to the edge of the roof that their new-found indifference to height was a trifle strained, Lackland headed uphill once more. He had warned the sailors to keep clear of the gun muzzle, and kept the weapon trained ahead of him; but there was no motion on the ridge, and no more rocks fell. Apparently the natives who had launched them had retreated to the tunnels which evidently led up from their city. This, however, was no assurance that they would not come out again; and everyone on and in the tank kept a sharp lookout for any sort of motion.

The channel they were climbing was not the same as the one they had descended, and consequently did not lead directly to the sled; but the Bree became visible some distance before they reached the top, owing to the tank’s height The crew members who had been left behind were still there, all looking with evident anxiety down into the city. Dondragmer muttered something in his own language concerning the stupidity of not keeping an all-around watch, which Barlennan repeated in amplified form in English. However, the worry proved fruitless; the tank reached the stranded sled, turned, and was hitched up to its load without further interference. Lackland, once more under way, decided that the giants had overestimated the effectiveness of the gun; an attack from close quarters — emerging, for example, from the concealed tunnel mouths which must shelter the individuals who started the rocks downhill — would leave the weapon completely helpless, since neither high explosive nor thermite shells could be used close to the Bree or her crew.

With great reluctance he decided that there could be no more exploration until the Bree had reached the waters of the eastern ocean. Barlennan, when this conclusion was offered for his consideration, agreed, though he made some reservations in his own mind. Certainly while the Flyer slept his own crew was going to keep working.

With the expedition once more under way and the tangible results of the interruption rapidly being transferred from tank roof to ship by leaping Mesklinites, Lackland made a call to Toorey, listened humbly to the expected blast when Rosten learned what he had been doing, and silenced him ass before with the report that much plant tissue was now available if Rosten would send down containers for it.

By the time the rocket had landed far enough ahead of them to preserve the Mesklinite nervous systems, had waited for their arrival, picked up the new specimens, and waited once more until the”tank had traveled safely out of range of its takeoff blast, many more days had passed. These, except for the rocket’s visit, were relatively uneventful. Every few miles a boulder-rimmed hilltop was sighted, but they carefully avoided these, and none of the giant natives were seen outside their cities. This fact rather worried Lackland, who could not imagine where or how they obtained food. With nothing but the relatively boring job of driving to occupy his mind, he naturally formed many hypotheses about the strange creatures. These he occasionally outlined to Barlennan, but that worthy was not much help in deciding among them, and Lackland got little of value from their conversations.

One of his own ideas, however, bothered him. He had been wondering just why the giants built their cities in such a fashion. They could hardly have been expecting either the tank or the Bree. It seemed a rather impractical way to repel invasion by others of their own kind, who evidently, from the commonness of the custom, could hardly be taken by surprise.

Still, there was a possible reason. It was just a hypothesis; but it would account for the city design, and for the lack of natives in the country outside, and for the absence of anything resembling farm lands in the neighborhood of the cities. It involved a lot of “iffing” on Lackland’s part even to think of such an idea in the first place, and he did not mention it to Barlennan. For one thing, it left unexplained the fact that they had come this far unmolested — if the idea were sound, they should by now have used up a great deal more of the quick-firer’s ammunition. He said nothing, therefore, and merely kept his own eyes open; but he was not too surprised, one sunrise when they had come perhaps two hundred miles from the city where Hars received his injuries, to see a small hillock ahead of the cavalcade suddenly rear up on a score of stubby, elephantine legs, lift as far as possible a head mounted on a twenty-foot neck, stare for a long moment out of a battery of eyes, and then come lumbering to meet the oncoming tank.

Barlennan for once was not riding in his usual station on the roof, but he responded at once to Lackland’s call. The Earthman had stopped the tank, and there were several minutes to decide on a course of action before the beast would reach them at its present rate of speed.

“Barl, I’m willing to bet you’ve never seen anything like that. Even with tissue as tough as your planet produces, it could never carry its own weight very far from the equator.”

“You are quite right; I haven’t. I have never heard of it, either, and don’t know whether or not it’s likely to be dangerous. I’m not sure I want to find out, either. Still, it’s meat; maybe. ”

“If you mean you don’t know whether it eats meat or vegetables, I’ll bet on the former,” replied Lackland. “It would be a very unusual plant-eater that would come toward something even larger than itself immediately upon sighting it — unless it’s stupid enough to think the tank is a female of its own species, which I very much doubt. Also, I was thinking that a large flesh-eater was the easiest way to explain why the giants never seem to come out of their cities, and have them built into such efficient traps. They probably lure any of these things that come to their hilltop by showing themselves at the bottom, as they did with us, and then kill them with rocks as they tried on the tank. It’s one way of having meat delivered to your front door.”

“All that may be true, but is not of present concern,” Barlennan replied with some impatience. “Just what should we do with this one? That weapon of yours that broke up the rock would probably kill it, but might not leave enough meat worth collecting; while if we go out with the nets well be too close for you to use it safely should we get in trouble.”

“You mean you’d consider using your nets on a thing that size?”

“Certainly. They would hold it, I’m sure, if only we could get it into them. The trouble is that its feet are too big to go through the meshes, and our usual method of maneuvering them into its path wouldn’t do much good. We’d have to get the nets around its body and limbs somehow, and then pull them tight.”

“Have you a method in mind?”

“No — and we wouldn’t have time to do much of the sort anyway; he’ll be here in a moment.”

“Jump down and unhitch the sled. I’ll take the tank forward and keep him occupied for a while, if you want. If you decide to take him on, and get in trouble later, you all should be able to jump clear before I use the gun.”

Barlennan followed the first part of the suggestion without hesitation or argument, slipping off the rear of the deck and undoing with a single deft motion the hitch which held the tow cable to the tank. Giving a hoot to let Lackland know the job was done, he sprang aboard the Bree and quickly gave his crew the details of the new situation. They could see for themselves by the time he had finished, for the Flyer had moved the tank forward and to one side, clearing their line of sight to the great animal. For a short time they watched with much interest, some astonishment, but no fear to speak of as the tank maneuvered with its living counterpart.

The creature stopped as the machine resumed its forward motion. Its head dropped down to a yard or so from the ground, and the long neck swung as far as possible first to one side and then the other, while the multiple eyes took in the situation from all possible angles. It paid no attention to the Bree; either it failed to notice the small movements,of the crew, or regarded the tank as a more pressing problem. As Lackland moved toward one flank, it slewed its gigantic body around to keep facing it squarely. For a moment the Earthman thought of driving it into a full hundred-and-eighty-degree turn, so that it would be facing directly away from the ship; then he remembered that this would put the Bree in his line of fire should he have to use the gun, and stopped the circling maneuver when the stranded sled was at the monster’s right. With that eye arrangement, it would be as likely to see the sailors moving behind it as in front, anyway, he reflected.

Once more he moved toward the animal. It had settled down, belly to the ground, when he stopped circling; now it rose once more to its many legs and drew its head back almost into its great trunk, in what was apparently a protective gesture. Lackland stopped once more, seized a camera, and took several photographs of the creature; then, since it seemed in no mood to press an attack, he simply looked it over for a minute or two.

Its body was a trifle larger than that of an Earthly elephant; on Earth, it might have weighed eight or ten tons. The weight was distributed about evenly among the ten pairs of legs, which were short and enormously thick. Lackland doubted that the creature could move much faster than it had already.

After a minute or two of waiting, the creature began to grow restless; its head protruded a little and began to swing back and forth as though looking for other enemies. Lackland, fearing that its attention would become focused on the now helpless Bree and her crew, moved the tank forward another couple of feet; his adversary promptly resumed its defensive attitude. This was repeated several times, at intervals which grew progressively shorter. The feinting lasted until the sun sank behind the hill to the west; as the sky grew dark Lackland, not knowing whether the beast would be willing or able to carry on a battle at night, modified the situation by turning on all the tank’s lights. This, at least, would presumably prevent the creature from seeing anything in the darkness beyond, even if it were willing to face what to it must be a new and strange situation.

Quite plainly, it did not like the lights. It blinked several ‘times as the main spotlight burned into its eyes, and Lackland could see the great pupils contract; then, with a wailing hiss that was picked up by the roof speaker and clearly transmitted to the man inside, it lumbered a few feet forward and struck.

Lackland had not realized that he was so close — or, more correctly, that the thing could reach so far. The neck, even longer than he had at first estimated, snapped to full length, carrying the massive head forward and a trifle to one side. As it reached full travel, the head tipped a trifle and came slashing sideways. One of the great tusks clanged resoundingly against the tank’s armor, and the main light went out in the same instant. Another, shriller hiss suggested to Lackland that the current feeding the light had grounded into the armor through some portion of the monster’s head; but he was not taking time out to analyze the possibility. He backed away hastily, cutting the cabin lights as he did so. He did not want one of those tusks striking a cabin port with the force it had just expended on the upper armor. Now only the running lights, mounted low in the front of the vehicle and set well into the armor, were illuminating the scene. The animal, encouraged by Lackland’s retreat, lurched forward again and struck at one of these. The Earthman did not dare extinguish it, since it would have left him effectively blind; but he sent a frantic call on the radio.

“Barl! Are you doing anything about your nets? If you’re not about ready for action, I’m going to have to use the gun on this thing, meat or no meat. You’ll have to stay away if I do; he’s so close that high explosive would endanger the tank, and I’ll have to use thermite.”

“The nets are not ready, but if you’ll lead him back a few more yards hell be downwind of the ship, and we can take care of him another way.”

“All right.” Lackland did not know what the other way could be, and was more than a little doubtful of its effectiveness, whatever it was; but as long as retreat would suit the captain he was prepared to co-operate. It did not for an instant occur to him that Barlennan’s weapon might endanger the tank; and, in all fairness, it probably did not occur to Barlennan either. The Earthman, by dint of repeated and hasty withdrawals, kept the tusks from his plating most of the time; the monster did not seem to have the intelligence to anticipate motion on his part. Two or three minutes of this dodging satisfied Barlennan.

He, too, had been busy in those minutes. On the leeward rafts, toward the dueling monster and machine, were four devices closely resembling bellows, with hoppers mounted above their nozzles. Two sailors were now at each bellows, and at their captain’s signal began pumping for all they were worth. At the same time a third operator manipulated — the hopper and sent a stream of fine dust flowing into the current from the nozzle. This was picked up by the wind and carried toward the combatants. The darkness made it difficult to estimate its progress; but Barlennan was a good judge of wind, and after a few moments of pumping suddenly snapped out another order.

The hopper crews promptly did something at the nozzle of the bellows each was tending; and as they did so, a roaring sheet of flame spread downwind from the Bree to envelop both of the fighters. The ship’s crew were already sheltered behind their tarpaulins, even the “gunners” being protected by flaps of fabric that formed part of their weapons; but the vegetation that sprouted through the snow was neither tall nor dense enough to shelter the fighters. Lackland, using words that he had never taught Barlennan, hurled the tank backward out of the flame cloud with a prayer for the quartz in his portholes. His adversary, though evidently as anxious to dodge, seemed to lack the necessary control. It lurched first one way, then the other, seeking escape. The flame died out in seconds, leaving a cloud of dense white smoke which gleamed in the tank’s running lights; but either the brief fire had been sufficient or the smoke was equally deadly, for the monster’s disorganization grew steadily worse. Its aimless steps grew shorter and feebler as the legs gradually lost the power to support its vast bulk, and presently it stumbled and rolled on-one side. The legs kicked frantically for a time, while the long neck alternately retracted and stretched to full length, lashing the fanged head frantically through the air and against the ground. By sunrise the only remaining motion, was an occasional — twitch of head or leg; within a minute or two thereafter all activity of the giant creature ceased. The crew of the Bree had already swarmed overboard and across the dark patch where the snow had boiled from the ground, bent on acquiring meat. The deadly white cloud was farther downwind now, and gradually settling. Lackland was surprised to note traces of black dust on the snow where the cloud had passed.

“Barl, what on Earth — or rather, on Mesklin — was the stuff you used for that fire cloud? And didn’t it occur to you that it might crack the windows in this tank?” The captain, who had remained on the ship and was near one of his radios, answered promptly.

“I’m sorry, Charles; I didn’t know what your windows are made of, and never thought of our flame cloud as a danger to your great machine. I will be more careful next time. The fuel is simply a dust which we obtain from certain plants-it is found as fairly large crystals, which we have to pulverize very carefully and away from all light.” Lackland nodded slowly, digesting this information. His chemical knowledge was slight, but it was sufficient to make a good guess at the fuel’s nature. Ignited by, light — burned in hydrogen with a white cloud — black specks on the snow — it could, as far as he knew, be only one thing. Chlorine is solid at Mesklin’s temperature; it combines violently with hydrogen, and hydrogen chloride is white when in fine powder form; methane snow boiled from the ground would also give up its hydrogen to the voracious element and leave carbon. Interesting plant life this world sported! He must make another report to Toorey — or perhaps he had better save this tidbit in case he annoyed Rosten again.

“I am very sorry I endangered your tank.” Barlennan still seemed to feel apologetic. “Perhaps we had better let you deal with such creatures with your gun; or perhaps you could teach us to use it. Is it, like the radios, especially built to work on Mesklin?” The captain wondered if he had gone too far with this suggestion, but decided it had been worth it. He could neither see nor interpret Lackland’s answering smile.

“No, the gun was not remade or changed for this world, Barl. It works fairly well here, but I’m afraid it would be pretty useless in your country.” He picked up a slide rule, and added one more sentence after employing it for a moment. “The farthest this thing could possibly shoot at your pole would be just about one hundred fifty feet.”

Barlennan, disappointed, said nothing further. Several days were spent in butchering the dead monster. Lackland salvaged the skull as a further protection from Rosten’s ire, and the cavalcade resumed its journey.

Mile after mile, day after day, the tank and its tow inched onward. Still they sighted occasional cities of the rock-rollers; two or three times they picked up food for Lackland which had been left in their path by the rocket; quite frequently they encountered large animals, some like the one Barlennan’s fire had slain, others very different in size and build. Twice specimens of giant herbivores were netted and killed by the crew to furnish meat, much to Lackland’s admiration. The discrepancy in size was far greater than that existing between Earthly elephants and the African pygmies who sometimes hunted them.

The country grew hillier as they progressed, and with the rising ground the river, Which they had followed intermittently for hundreds of miles, shrank and split into numerous smaller streams. Two of ‘these tributaries had been rather difficult to cross, requiring that the Bree be unlashed from the sled and floated across at the end of a towrope while tank and sled drove below the surface on the river bed. Now, however, the streams had become so narrow that the sled actually bridged them and no such delays occurred.

At long last, fully twelve hundred miles from where the Bree had wintered and some three hundred south of the equator, with Lackland bowing under an additional half gravity, the streams began to bear definitely in the general direction of their travel. Both Lackland and Barlennan let several days pass before mentioning it, wishing to be sure, but at last there was no more doubt that they were in the watershed leading to the eastern ocean. Morale, which had never been low, nevertheless improved noticeably; and several sailors could now always be found on the tank’s roof hoping for the first glimpse of the sea as they reached each hilltop. Even Lackland, tired sometimes to the point of nausea, brightened up; and as his relief was the greater, so proportionately greater was his shock and dismay when they came, with practically no warning, to the edge of an escarpment; an almost sheer drop of over sixty feet, stretching as far as the eye could see at right angles to their course.