Free The Outward Urge by John Wyndham Page A

would be able to dispute their rights with greater confidence.
    Some six months later, the smaller British expedition set down in the crater of Archimedes, with the Russian six hundred miles away beyond the Apennine Mountains to the south, and the American four hundred miles or so to the north-east. There, in contrast with their intensively burrowing neighbours, they proceeded to establish themselves on the surface. They had, it was true, one drilling-machine, but this, compared with the huge tunnelling engines of the others that had cost a good many times their weight in uranium to transport, was a mere toy which they employed in sinking a series of six-foot diameter pits.
    The Flanderys Dome, essentially a modification of Domes used in the Arctic for some years, was a simple affair to erect. It was spread out on a levelled part of the crater floor, coupled with hoses, and left to inflate. With only the light gravity of the moon weighing down its fabric, the outer casing was fully shaped at a pressure of eight pounds (Earth) per square inch, at fifteen it was perfectly taut. Then the contents of the various rockets and containers went into it through the airlocks, or the annuli. The air regenerating plants were started up, the temperature controls coupled, and the work of building the station inside the dome could begin.
    The Americans, Troon recalled, had been interested. They reckoned it quite an idea for use on a moon where there did not happen to be any Russians about; but on one where there were, they thought it plain nuts, and said so. The Russians themselves, he remembered with a smile, had been bewildered. A flimsy contrivance that could be completely wrecked by a single, old-fashioned H.E. shell was in their opinion utter madness, and a sitting temptation. They did not, however, yield to the temptation since that would almost certainly precipitate untimely action by the Americans. Nevertheless, the presumption of a declining Power in arriving to settle itself blandly and unprotected in the open while two great Powers were competing to tunnel themselves hundreds of feet into the rock was a curious piece of effrontery. Even a less suspicious mind than the Russian could well have felt that there was something here that was not meeting the eye. They instructed their agents to investigate.
    The investigation took a little time, but presently the solution forthcame - an inconvenient clarification. As had been assumed, the pits that the British had been busily drilling at the same time that they built their station into the Dome were missile-shafts. This was similar to the work being done by the other two parties themselves - except that where the Americans also used pits, the Russians favoured launching ramps. The more disturbing aspect of it came to light later.
    The British system of control, it appeared, was to use a main computing-engine to direct the aim and setting of any missile. Once the missile had been launched, it was kept on course by its own computer and servo systems. The main computer was, unlike the rest of the station, protected m a chamber drilled to a considerable depth. One of its more interesting features was that in certain conditions it was capable of automatically computing for, and dispatching, missiles until all were gone. A quite simple punched-card system was used in conjunction with a chronometer; each card being related to a selected target. One of the conditions which would cause this pack of cards to be fed to the computer was a drop in the station’s air-pressure. Fifteen pounds per square inch was its normal, and there was allowance for reasonable variation. Should the Dome be so unfortunate, however, as to suffer a misfortune sufficient to reduce the air-pressure to seven pounds, the missile-dispatching mechanism would automatically go into action.
    All things considered, it appeared highly desirable from the Russian point of view that the Flanderys Dome should not suffer any such