"Jack, Jack, my boy." The voice came from a great distance, slowly penetrating the great cloud which hung over him. "Jack, what's the matter with you?" He realized that someone was talking to him. With a mighty effort, he opened his eyes and endeavored to distinguish the speaker among the thousands of objects which whirled before his eyes. At last things settled down, and he saw the anxious faces of Erickson and Captain Linet bending above him.

"Somebody was in my cabin, and slugged me over the head with a black-jack when I came in. Look at the wall-cabinet, will you, professor, and see if any of the papers are missing?"

The professor stepped over to one side of the room, and bent to examine the compartment set in the solid metal of the wall.

"Holden," he cried, "the intruder tried to open the cabinet, but was unable to do so, or else you came back sooner than he had expected. There are tool marks all around the lock."

"That means," exclaimed Captain Linet, "that the man either has tools in his cabin, or has access to the machine shop here on board."

Scarcely had he spoken when the floor leaped beneath their feet, a deafening roar sounded from the bow, and the lights went out. Sounds of running feet came from the corridor. The three men picked themselves up from the positions into which they had been thrown by the force of the shock, and rushed to the door.

The emergency lights had been switched on, and they could see fairly well by the dim illumination. They hurried into the pilot house at the bow. Edwards was struggling with the controls, pale but determined.

"There's something wrong with the steering apparatus we've run into a group of tiny meteorites, but, thank God, they didn't hit hard enough to penetrate the shell. The other ships seem to be in good shape; they're standing by a few hundred miles away, for I've signaled them not to get themselves tangled up with this shower."

At that moment a breathless tube-man came running in.

"Report for you, sir, from the tube-room. Someone tampered with the timing device that controls the feeding of the charges. We can have it repaired in a few hours."