CHAPTER X. SQUELCHED BY AN OSTRICH. Unlike Bob, Jack after leaving Ali took cautious observations from time to time to enable him to keep the ostrich herd in sight. He realized the possibility of being deflected from his course in passing behind the sand dunes, but by frequent halts when he would compel his camel to kneel and, retaining the long led rope so as to prevent the animal’s wandering, climb to the top of a sand dune, and lying there, swing his glasses on the distant birds, he managed to make a wide arc about the herd without going astray. When a half hour had elapsed, he rose into sight as agreed and a moment later saw, through his glasses, Ali making for the ostrich herd. Then he swung his glasses again over the horizon in the direction where Bob was supposed to have taken post. But he was unable to see any sign of his comrade. A somewhat higher mass of dunes far off the course and more distant caught his eye, and he entertained the fleeting thought that, perhaps, Bob in wandering behind the sand dunes had gotten mixed up among the distant hills. But he had little time for reflection because at that moment he saw Ali start off in pursuit of the ostrich nearest him who, seeing his approach, headed away fleetly into the desert. Jack’s first impulse was to dash forward and join in the chase himself, but he remembered Ali’s caution and held his position. Ali’s camel was on a tangent to the flight of the ostrich, and Jack could see his companion’s intention was to head off the big bird and chase it toward him. In the meantime, the more distant members of the herd, a dozen great birds, had taken alarm and were galloping away on a course that lay midway between Ali and Jack, whom apparently they had now sighted. What a picture it all made, thought Jack. For a while, he sat his camel, lost in admiration of the sight. The vast waving floor of the desert, with here and there low clumps of bush; the great birds, black-bodied, beautiful under the flood of golden, dazzling sunlight, fleeing fleetly in twenty-five foot bounds; apart from his fellows the one great ostrich, gradually drawing closer to Jack, with the ungainly camel humping along in the rear and to one side, continually turning the ostrich so he could not gain the open desert behind Jack’s camel. In the midst of his absorption, Jack started. Was that a shot? He listened. But no repetition came. So faint had been the sound that, perhaps, his ears had deceived him. Certainly, if it were a shot it could come only from Bob, yet Bob was not in sight. And just as certainly as Bob would shoot, if he were lost, he would fire a whole volley. Jack listened with strained attention. Not a sound. He swept the whole northern horizon, in the direction Bob had taken, with his glasses.