Knife in one hand, the Professor hurled himself forward and caught the bird in the grip of the other. Instantly from the doorway sprang a monstrous mechanism on stilts, flexible tentacles of metal reaching out and wrapping themselves around the Professor. Talbot leaped to the Professor's assistance. The mechanism fought like a live thing. In vain he strove to wrench the tentacles free of the Professor. One of them lashed out and took him by the thighs in a crushing grasp. But the Professor had the bird by the throat. Both of his hands were free. Back, he forced its head, back. The mechanism seemed to falter in the attack, as if bewildered. Across the exposed throat the Professor drew the gleaming blade. Flesh, tendons and arteries gave, blood spurted, and in the same moment the tentacles fell away from Talbot and the Professor and withdrew with a dull clang. The Professor released the bird and it dropped to the floor. "It is the birds' mentality that directs those mechanisms," said the Professor, pointing to the now harmless machine. Apparently the brief but terrific battle had passed unnoticed, no alarm being given. Now the corridor twisted. The two men came to where a deep well was sunk in the floor. To one side a star-wheel revolved smoothly. Out of the depths came the steady throb of machinery. Cautiously peering over the edge, Talbot saw a sight he would never forget. He did not need the Professor's whispered words to tell him that here was the source of the deadly attack being waged against earth. Motionless birds perched in front of bizarre machines; lights waxed and waned; a cannon-like device, or funnel, shot a column of light into a screen, and through the column of light moved a steady procession of round objects the size of plums. "The drifting globes being shot through to earth," whispered the Professor, "and our only hope. Listen, the birds are intent on their machines, their backs to the star-wheel. We will descend, throw ourselves into the column of light, seize hold of a globe, and...." He did not need to finish. Talbot understood in a flash. They would be dragged to their own world by the weapons hurled at it. "Of course that column of light may kill us," went on the Professor tensely. "Or we may be blown up on the other side. Your Mexican friend hasn't touched off that explosive gas yet, because--But we've not a moment to lose. Follow me." The tip of the star-wheel went up, over, descended. The blood was roaring in Talbot's ears. "Now!" hissed the Professor. "Now!" Together they rushed forward. Talbot's foot slipped. The heart leaped into his throat. He never remembered reaching the column of light; but suddenly he was in it, blinded, dazed. His clutching hands closed on something small and hard.