When Lawrence had been flying for about twenty minutes he became somewhat uneasy at a sudden freshening of the wind, which blew in uncertain gusts from the mountains on his right. Since passing the Kalmucks he had kept fairly close to the river, but when the machine began to rock under these invisible eddies he thought it the safer course to rise to a considerable height. The morning air was so exhilarating, and the view of endless snow-capped heights and pine-clad ravines so superb, that only the intense cold, of which he was now conscious in spite of the summer sun, checked his ascension. On the left stretched the Pamirs, backed by peak after peak of some of the loftiest and most majestic mountains in the world. In front and on the right the Himalaya range merged into the Hindu Kush. Huge masses of cloud rolled up and down the rugged faces of the mountains, causing moment by moment wonderful changes in their aspect. Some of the peaks seemed to have covered themselves with an umbrella of fleecy billowy wool as a shield against the kindling sunbeams. The enormous scale of this panorama defied perspective and gave a false idea of distance. Lawrence knew that peaks which, clearly limned against the sky, might be thought to be ten or fifteen miles away, were in reality more than a hundred. But for the urgency of his mission, he felt that he would have liked to sail on and on in this empyrean height, exploring regions never trodden by the foot of man. All the time, Fazl kept a keen eye on the track and the river, winding along hundreds, even thousands, of feet below. The hill-tower lay somewhat to the west of the road which the Appletons had travelled with Major Endicott several months before, and from this road the track leading to the mine branched. The Gurkha knew the country pretty well. Fast as the aeroplane flew, he distinguished without hesitation the junction of the roads, and at his word Lawrence altered his course and, leaving the valley, steered over the hills on his right hand. Very soon Fazl was able to descry the hill-tower in the far distance. The aeroplane was flying at the rate of at least a mile a minute; but minute after minute passed, and yet the tower seemed little nearer. When at last Lawrence had come close enough to it to be able to distinguish its general features, he saw that it was a single square-built tower of the usual Afghan type, perched on a small hill that rose sharply from the surrounding country. The side nearest him overhung an almost perpendicular declivity. Though solidly constructed in appearance, it was little more than a ruin. The top had partially fallen away, and in the wall facing him there was a long jagged fissure.