Hunter twisted in his seat, bent over, and began to examine the tank. "Can’t find any leak," he said presently. "If there’s one, it’s out of reach. How’s the gauge?" "At this rate we shall be done in another ten minutes." "Whew! How much farther to go?" "At least twenty miles, perhaps more. I wish we had come straight. There’s absolutely no chance of getting back before the petrol gives out. Where’s the enemy?" "Still on our port side, going strong. It looks as if she means to chase us, thinking we’re running away. We shall have to fight now, shan’t we?" "Yes. We’re bound to come down in a few minutes, and if we don’t tackle her at once it’s all up with us. How far is she off?" "About a couple of miles, I think, and about the same height. Her course is between us and Enos, worse luck!" "Wish we had a machine-gun! I’ll come round; take a shot when we’re within range, and for goodness’ sake cripple her." He brought the seaplane round in an easy curve, at the same time climbing to get above the enemy. His eye was all the time on the rapidly falling gauge. The aviatik held on its course for a little, then wheeled to the south-west, as if to cut the seaplane off. It was clear that the enemy airmen had no wish to avoid a fight. Burton’s wheeling movement had now made his course almost due east, so that the two machines were rushing obliquely towards each other at the rate of about a hundred miles an hour. When they crossed, Burton was slightly ahead of the enemy, and, to his surprise, somewhat lower. At almost the same moment Hunter and the enemy’s observer opened fire with their rifles, but each was handicapped by the fact that he was firing from right to left, and no damage seemed to have been done on either side. As soon as Burton had passed the enemy, he banked his machine and wheeled to the left, climbing as rapidly as possible to make good the deficiency in height. The aviatik also made a spiral movement to the left, with the result that in a few seconds the machines were once more converging on each other. This time, however, Burton was slightly to the rear of the enemy, and when their tracks crossed, he shot up behind it on its left. The aviatik, a second or two too late, made a desperate effort to edge away eastward, but the movement only brought the two planes closer together. "We can’t stick it another minute," gasped Burton. Hunter did not reply. He had dropped his rifle and seized his automatic pistol. The machines were at point-blank range. Hunter fired. The enemy’s observer screwed himself round in his seat to reply. Aiming at the pilot, Hunter sent a stream of bullets from his pistol. The pilot fell forward. For a moment the aeroplane rocked and seemed on the point of capsizing. Then the observer seized the controls, and, with a recklessness that bespoke inexperience or want of skill, began a perilously steep volplané. [Illustration: An aerial somersault]