Everything depended on what sort of surface he was flying above. If there were flat open fields he must catch sight, however shadowy it might be, of them before touching anything. If there were trees or buildings below, the first sight he got might be something looming up before him a fraction of a second before he hit. Down, steadily and gradually, but still down--down ... then, UP--suddenly and steeply, his hand jerking the throttle wide open, the engine roaring out in deafening notes that for all their strength could not drown the thumping of his heart and the blood drumming in his ears. A hundred feet he climbed steeply; but even then, with the panic of immediate peril gone, he kept on climbing in narrow turns up into the sunlight again. He had had a deadly narrow escape, had been so intent on staring down for the ground that almost before he knew what was happening he had flashed close past something solid, something that his wing-tips catching would have meant death--a straight upright pillar, then another, with faint pencilled lines running between them--a ship's masts and rigging. And as he shot up, almost straight up, he had a quick glimpse of another three shadowy masts jerking downwards into obscurity before and then beneath him. He must be over a harbour, or dock, or perhaps some sort of canal basin. He kept his upward course until he was in sunlight again, carefully examined his oil and petrol gauges and his compass, and set a northerly course. The mist might be over all France; he would make a try back for England. He held on until he had run his main petrol tank out, switched on to the gravity "emergency tank" set on the top plane, and kept steadily on his course. He had an hour's petrol there, and that ought, he figured, to take him well over England and inland. He decided to keep going until he could see signs of the mist thinning, or until his petrol ran almost out; but when it was about half empty, and he thought he must be back over the Channel and a good many miles inland, he slid down through the mist on the chance of being able to see the ground below it. He went down to a hundred feet, lower, could see nothing, opened his engine out again and began to climb. Then he had another hair-raising deadly scare. He saw the mist in front of him suddenly begin to darken, to solidify, to take shape, to become a solid bulk stretching out and thinning away to grey mist to either side, above him, and below him.