It was hardly apparent, but true. Ever so slightly, the snub nose of the ZX-1 was swaying from side to side as it sped through the air; ever so slightly, her massive stern directional-rudders were wavering.
She was less than a mile away now. At that time, there were no other planes in sight; none flying in that vicinity save Chris's. He glued his eyes to the telescopic sight. A moment later, sheer horror swept his face.
"Good God!"
The scout leaped as its throttle rammed down. The gleaming, thousand-foot shell of the ZX-1 roared by it at equal altitude, making it a puny fly-speck in the sky. But the fly-speck was faster. It turned in a screaming bank; it straightened; it lunged back after the swaying, retreating mammoth like a whippet, lower, now, than its quarry. It maneuvered expertly as it gained, for one of the best pilots of the service was at its controls, and there were deep lines graven in his face, lines of anguish and intolerable suspense.
Through the telescopic sight, Chris had not seen a single white-clad figure standing beside the glass ports of the dirigible's control car. But he had seen, slung from the rack along her belly, a single plane—the same rather peculiar-looking plane he had seen hanging beneath the rack of the ZX-2 a few minutes before she had gone down in flames!
And in that plane, he knew surely, was the answer to the mystery.
Speed cut to just a trifle more than the dirigible's. Chris passed a few feet underneath the huge expanse of her lower directional rudder. From so close, its uncontrolled wavering was terrifying.
His faculties were concentrated on the task of sliding the scout's clamp into the groove of the plane rack, but he was also surveying the lone airplane hanging from it. A powerful machine, painted in Navy colors, a peculiar knob on the upper side of each half of the top wing gave it its unfamiliar appearance. Its pilot was obviously aboard the dirigible, working....
Closer and closer the scout crept, quarter-way now along from the stern of the massive bulk that loomed above it, and within fifty feet of the third clamp in the rack. Touchy work, maneuvering into it, with the ZX-1 yawing as she was, and the need for haste desperate. Chris's hands were glued to the stick: his nerves were as tight as violin strings. Then, when only ten feet from the rack clamp, he gave a startled jump of uncomprehending amazement.