Mission of Gravity

by Clement Hal

The situation reached a climax at about two hundred gravities, with more than a third of the sea journey behind them. The minutes of daylight were longer now as spring progressed and the Bree moved ever farther from her sun, and the sailors were relaxing accordingly. The individual who had the bailing job was not, therefore, very attentive as he pulled the canoe up the stern rafts and climbed over its gunwale. He was aroused immediately thereafter. The canoe, of course, settled a trifle as he entered; and as it did so, the springy wood of the sides gave a little. As the sides collapsed, it sank a little farther — and the sides yielded more — and it sank yet farther-Like any feedback reaction, this one went to completion in a remarkably short time. The sailor barely had time to feel the side of the canoe pressing inward when the whole vessel went under and the outside pressure was relieved. Enough of the cargo was denser than methane to keep the canoe sinking, and the sailor found himself swimming where he had expected to be riding. The canoe itself settled to the end of its towrope, slowing the Bree with a jerk that brought the entire crew to full alertness.

The sailor climbed back into the Bree, explaining what had happened as he did so. All the crew whose duties did not keep them elsewhere rushed to the stern, and presently the rope was hauled in with the swamped canoe at the end of it. With some effort, the canoe and such of its load as had been adequately lashed down were hauled aboard, and one of the sets turned to view it. The object was not very informative; the tremendous resilience of the wood had resulted in its recovering completely even from this flattening, and the canoe had resumed its original shape, still without leaks. This last fact was established after it had once more been unloaded.

Lackland, looking it over, shook his head and offered no explanation. “Tell me just what happened — what everyone who saw anything at all did see.”

The Mesklinites complied, Barlennan translating the stories of the crewman who had been involved and the few others who had seen the event in any detail. It was the first, of course, that provided the important bit of information.

“Good Earth!” Lacklaiid muttered, half aloud. “What’s the use of a high school education if you can’t recall it when needed later on? Pressure in a liquid corresponds to the weight of liquid above the point in question — and even methane under a couple of hundred gravities weighs a good deal per vertical inch. That wood’s not much thicker than paper, either; a wonder it held so long.” Barlennan interrupted this rather uninformative monologue with a request — for information.

“I gather you now know what happened,” he said. “Could you please make it clear to us?”

Lackland made an honest effort, but was only partly successful. The concept of pressure, in a quantitative sense, defeats a certain number of students in every high school class.

Barlennan did get the idea that the deeper one went into the sea the greater was the crushing force, and that the rate of increase with depth went up along with gravity; but he did not connect this force with others such as wind, or even the distress he himself had experienced when he submerged too rapidly in swimming.

The main point, of course, was that any floating object had to have some part of itself under the surface, and that sooner or later that part was going to be crushed if it was hollow. He avoided Dondragmer’s eye as this conclusion was reached in his conversation with Lackland, and was not comforted when the mate pointed out that this was undoubtedly where he had betrayed his falsehood when talking to Reejaaren. Hollow ships used by his own people, indeed! The islanders must have learned the futility of that in the far south long since.

The gear that had been in the canoe was stowed on deck, and the voyage continued. Barlennan could not bring himself to part with the now useless little vessel, though it took up a good deal of space. He disguised its uselessness thinly by packing it with food supplies which could not have been heaped so high without the sides of the canoe to retain them. Dondragmer pointed out that it was reducing the ship’s flexibility by extending the length of two rafts, but the captain did not let this fact worry him.