Police craft, of course.

The girl's pale face was watching and he knew that she also was aware of the pursuit. To those who followed their space-ship could be but a dwindling mote that floated out of place in the pattern of encircling stars.

Yet they had him! He read that conviction deep in her listless eyes. The jaws of a gigantic trap were closing down about him in space. With the superior speed of the Marshall gravity-impelled speedsters, overhauling was certain, and then it would be a mere matter of clamping him in magnetic grapples and making up a forced boarding party in space toggings.

He pushed the controls down, built the discharge blasts to their limit, and mopped sweat from his brow.

"They'll catch you, won't they?" He was surprised at the limpid words. Alyce was lying on the swinging spring-couch, watching him in a detached lethargy.

"Good girl!" he exclaimed jubilantly. Her faint interest was evidence that there was still sap left in her body. "No, I don't think they'll catch us. Now, don't move around and exert yourself. Just remember that I'm your doctor now, and a pretty good doctor at that."

Right now those radiant, penetrating rays might be going through the hulls of the ship, passing through diseased cell tissue, rearranging the cellular patterns. He was determined not to frighten her. Words might soothe her. So he pointed to the dots in the rear vision screens, which were becoming larger.

"They're getting closer! That's because they're using the gravity repulsion system, and I'm still using rockets. The rockets are on full blast. There are about ten police ships hot on my trail. If I depended entirely on rocket blasts, I'd never get away from anti-gravity chasers."

As he spoke he was engrossed in making changes on the oval mechanism board.

"My new drive doesn't use an explosive blast," he explained. "The fuel doesn't explode, but changes into primitive radiation! This radiation shimmers away—at almost the speed of light. Due to its increased mass with its enormous velocity, it will exert an enormous force in the opposite direction."

An instrument on the board cackled, and he flipped a switch. A telescreen began to lighten. Those pursuit spacers were dangerously close now. Close enough to see uniformed men standing on their bridges, peering through glassite. From the nearest cylindrical shape a 

 Prev. P 8/23 next