"And nothing else! Remember, you're going back a hundred and ten million years and any action on your part might have an incalculable effect on the present. You might wipe out the whole human race by stepping on one furry little animal who was its ancestor. I think that moving a rock slightly will be a good first innocuous experiment, but be careful!" They moved toward the great transparent housing at the end of the laboratory. Through its foot-thick walls, the red, black and silver equipment in one corner shone hazily. An enormous lever protruded from the maze of wiring like a metallic forefinger. "You should arrive in the Cretaceous Period, the middle period of the age of reptiles. Most of North America was under water, but geological investigation shows an island on this spot." "You been over this sixteen times. Just show me what dingus to pull and let me go." Ruddle executed a little dance that a student of modern ballet might have called "Man with High Blood Pressure about to Blow his Top." "Dingus!" he screeched. "You don't pull any dingus! You gently depress--gently, you hear!--the chronotransit, that large black lever, thus sliding the quartzine door shut and starting the machine. When you arrive you lift it--again gently--and the door will open. The machine is set to go back a given number of years, so that fortunately you have no thinking to do." McCarthy stared down at him easily. "You make a lot of cracks for a little guy. I'll bet you're scared stiff of your wife." "I'm not married," Ruddle told him shortly. "I don't believe in the institution." He remembered. "Who was talking about marriage? At a time like this.... When I think of allowing a stubborn, stupid character like yourself to run loose with a device having the immense potentialities of a time machine--Of course, I'm far too valuable to be risked in the first jerry-built model." "Yeah," McCarthy nodded. "Ain't it the truth." He patted the check protruding from his sweater pocket and leaped up into the machine. "I'm not." He depressed the chronotransit lever--gently. The door slid shut on Professor Ruddle's frantic last word, "Goodbye, Turtleneck, and be _careful_, please!" "Gooseneck," McCarthy automatically corrected. The machine seemed to jerk. He had a last, distorted glimpse of Ruddle's shaggy white head through the quartzine walls. The professor, alarm and doubt mixed on his face, seemed to be praying. * * * * * Incredibly bright sunlight blazed through thick bluish clouds. The time machine rested on the waterline of a beach to whose edge the lushest jungle ever had rushed--and stopped abruptly. The semi-transparent walls enabled him to see enormous green masses of horsetails and convoluted ivy, giant ferns and luxuriant palms, steaming slightly, rich and ominous with life. "Lift the dingus _gently_," McCarthy murmured to himself.