"Bravo!" Mr. Swift applauded encouragingly. But the next instant Exman gave up! He slid back to the floor again with a heavy bump. Then he began whirling and darting about madly. "Good night! Exman's gone berserk!" Tom cried. Now wafts of smoke could be seen issuing from the robot's wheels. He was banging wildly about the laboratory, leaving a trail of havoc. Bud, who had returned, opened the door to come in. Instantly Exman lunged toward him, antennas sparking fiercely and wheels smoking. Bud slammed the door hastily. The Swifts, too, found it wiser to take cover. They crouched behind a lab workbench until the frenzy was over. Presently Exman subsided and rolled to a complete standstill. "Good grief!" Tom stood up cautiously and eyed the creature. It made no further move. Bud poked his head through the doorway for a wary look, then re-entered the laboratory. "What made him blow his top?" Bud asked. Then Tom heard a quiet chuckle from his father. "Actually, boys," the elder scientist said, "I think we should be encouraged." "_Encouraged?_" Tom stared at his father. [Illustration (Tom Jr. and Tom Sr. watch as Exman tries to climb stairs)] Mr. Swift nodded. "Yes, the whole thing was rather a noteworthy reaction. I believe Exman was displaying a fear complex about navigating up those stairs." Tom gasped, then broke out laughing. "Dad, you're right! I'll bet when its body tilted over, the brain wasn't sure whether the gyro would keep it from being wrecked. It just shows Ole Think Box is getting more human all the time!" Bud ventured to pat Exman on its "back." "Relax, kid," he said with a chuckle. "You're among friends and we wouldn't dream of letting you get hurt. You're too valuable!" Mr. Swift stroked his jaw thoughtfully. "Valuable, yes, if we can only get it to communicate. Tom, I believe the first project we should work on is a way to make Exman talk." After the debris had been cleaned up, the two scientists pulled up stools to the workbench and began to discuss the problem. Bud, seeing them absorbed, and realizing the discussion would soon be far beyond his depth, snapped a grinning salute at Exman and quietly left the laboratory. "Dad, the toughest part won't be the speech mechanism itself," Tom pointed out. "There are several ways we could handle that--by modulating a column of air, for instance, or by some sort of speaker diaphragm. The real stumper will be how to teach him our spoken language." Mr. Swift nodded. "I'm afraid you're right. If the inhabitants of Planet X communicate telepathically, or by some sort of wave transfer, they may have long since forgotten any concept of a spoken language." The Swifts batted several ideas back and forth. Then Tom snapped his fingers. "Wait, Dad! We have the answer! The electronic brain!" Mr. Swift's eyes lighted up. "Of course! The machine already translates the space code into written English. All we need do is add a device to convert the machine's impulses into sound!"