The Collected Stories of Arthur C. Clarke by Arthur C. Clarke

weren’t!’
    II
    During the next two weeks ship after ship dropped down beyond Pico and, after an initial outburst of speculation, the astronomers ceased to comment on the sight. Quite obviously something important was going on out in the Sea and the theory of the uranium mine was generally accepted because nobody could think of a better.
    Presently the Observatory staff began to take their energetic neighbours for granted and forgot about them except when rocket glare fogged important photographic plates. Then they went storming in to see the Director, who calmed them down as best he could and promised to make the appropriate representations in the proper quarters.
    With the coming of the long lunar day Jamieson and Wheeler settled down to the tedious work of analysing the data they had collected during the night. It would be fourteen days before they saw the stars again and could make any further observations. There was plenty to do, for an astronomer spends only a very small portion of his time actually working with his instruments. The most important part of his life is spent sitting at a desk piled with sheets of paper, which rapidly become covered with mathematical calculations or doodles, according to the flow of inspiration.
    Though both Wheeler and Jamieson were young and keen, an unbroken week of this was quite enough for them. In the slow cycle of lunar time it was generally realised that tempers began to get frayed around midday and from then until just before nightfall there was usually something of an exodus from the Observatory.
    It was Wheeler who suggested they take one of the Observatory tractors and head toward Pico on a voyage of exploration. Jamieson thought it was an excellent scheme though the idea was not as novel to him as to his friend. Trips out into the Sea of Rains were a popular diversion among the astronomers when they felt they had to get away from their colleagues.
    There was always the chance of finding something interesting in the way of minerals or vegetation but the main attraction was the superb scenery. Also there was a certain amount of adventure and even danger about the enterprise that gave it an additional charm. Not a few tractors had been lost and although rigorous safety precautions were enforced there was always a chance that something might go wrong.
    The almost complete absence of any atmosphere on the Moon had made economical flying impossible since rockets could not be used for journeys of only a few score miles. So practically all short-range lunar travel was done in the powerful electric tractors universally known as Caterpillars or, more briefly, ‘cats’.
    They were really small spaceships mounted on broad tracks that enabled them to go anywhere within reason, even over the appallingly jagged surface of the Moon. On fairly smooth terrain they could do up to eighty miles an hour but normally they were lucky to manage half that speed. The low gravity enabled them to climb fantastic slopes and they could if necessary haul themselves out of vertical pits by means of their built-in winches. One could live in the larger models for months at a time in reasonable comfort.
    Jamieson was a more-than-expert driver and knew the road down the mountains perfectly. As lunar highways went it was one of the best and carried a good deal of traffic between the Observatory and the port of Aristillus. Nevertheless for the first hour Wheeler felt that his hair would never lie down again.
    It usually took newcomers to the Moon a long time to realise that slopes of one-in-one were perfectly safe if treated with respect. Perhaps it was just as well that Wheeler was a novice for Jamieson’s technique was so unorthodox that it would have filled a more experienced passenger with real alarm.
    Why Jamieson was such a desperate driver was a paradox that had caused much discussion among his colleagues. Normally he was painstaking and careful, even languid in his movements. No one had ever seen him