don’t know. But I will say this—if more uranium does turn up and Earth doesn’t let the Federation have a bigger share of it, then we shall be in the wrong.’ ‘I don’t think that’s likely to happen.’ ‘Don’t be so sure. As old Mole said, there are a lot of people on Earth who are afraid of the Federation and don’t want to give it any more power. The Federation knows that and it may grab first and argue afterwards.’ ‘Hm. Then it’s nice to know that our friends out by Pico aren’t mining the stuff, after all,’ said Wheeler thoughtfully. ‘ Ouch —was that necessary?’ ‘Sorry. But if you will keep me talking you can’t expect me to avoid all the cracks. Looks as though the suspension wants adjusting. I’ll have to turn Ferdy in for an overhaul when we get back. Ah, that’s Mount Helicon coming up over there. No talking while I concentrate on the driving for the next few miles—the next section’s a bit tricky.’ The tractor turned northward and slowly the great wall of the beautiful Sinus Iridum —the Bay of Rainbows—rose over the horizon until it stretched east and west as far as the eye could see. So overwhelming was the sight that Wheeler was voluntarily silent and sat for the next twenty miles without a word while Jamieson drove the machine toward the three-mile-high cliffs ahead. He remembered his first glimpse of the Sinus Iridum through a two-inch telescope on Earth many years ago—it seemed scarcely possible that now he was actually skirting its towering walls. What unbelievable changes the twentieth century had brought! It needed a considerable effort to realise that at its beginning man had not even possessed flying machines, still less dreamed of crossing space. The history of two thousand years seemed to have been crowded into the single century with its vast technical achievements and two tremendous wars. In its first half the air had been conquered more thoroughly than had the sea in all the millennia before. In its closing quarter the first crude rockets had reached the Moon and the age-long isolation of the human race had ended. Within a single generation there were children to whom the word ‘home’ no longer conveyed the green fields and blue skies of Earth, so swift had been the colonisation of the inner planets. History, it has been said, never repeats itself but historical situations recur. Inevitably the new worlds began to loosen their ties with Earth. Their populations were still very small compared with those of the mother world but they contained the most brilliant and active minds the race possessed. Free at last from the crushing burden of tradition they planned to build civilisations which would avoid the mistakes of the past. The aim was a noble one—it might yet succeed. Venus had been the first world to declare its independence and set up a separate government. For a little while there had been considerable tension but good sense had prevailed and since the beginning of the twenty-first century only minor disagreements had disturbed relations between the two governments. Ten years later Mars and the four inhabited moons of Jupiter—Io, Europa, Ganymede and Callisto—had formed the union which was later to become the Federation of the Outer Planets. Wheeler had never been to any of these outer worlds. Indeed this was the first time he had even left his native Earth. Like most terrestrials he was a little scared of the Federation though the scientist in him made him admire many of its achievements. He did not believe in the possibility of war but if there were ‘incidents’—as earlier statesmen would have put it—his loyalties lay with Earth. The tractor rolled to a halt and Jamieson got up from the controls, stretching himself mightily. ‘Well, that’s enough for today. Let’s have some food before I turn cannibal.’ One corner of the tractor was fitted up as a tiny galley but the two explorers were much too lazy to use it and had