talking about precision work now, and I mean _pree_-cision!" Throughout the day Ken, too, felt increasing doubts about their ability to carry off the project. It would be a task of tremendous delicacy to analyze such microscopic samples as they might succeed in obtaining. Microchemical methods would be necessary, and none of them had had any experience in that field. His father was an expert with these methods and though he might scold them for tackling such a difficult project, he'd help them, Ken thought. He always had. This was no ordinary project, however. Ken had no idea how seriously scientists in general were considering the comet as the offender, but certainly they must be working frantically on the problem of the mechanical disorder. Unless they found another cause very soon, they were certain to turn to an analysis of the comet's tail. It would be very satisfying if Ken's group could actually be in the vanguard of such a development. He tried to ridicule his own conviction that the comet held the key. He had no reason whatever for such a belief, except the fact of the comet's universal presence. How it could stop an automobile engine or a railroad train was beyond his wildest imaginings. But there was nothing else. Nothing at all. On the way home after school, there seemed to Ken to be a subtle change that had come over the valley since morning. Along the streets, cars were parked in front of houses to which they did not belong. Little knots of people were standing about, talking in hushed tones. The comet was aflame in the sky. There seemed to be not merely an awe and an uneasiness in the people, but a genuine fear that Ken could not help absorbing as he moved past them on the sidewalks. Their faces were yellow and flat under the glare of the comet, and they looked at him and at each other as if they were strangers in an alien land. Almost without being aware of it, Ken found himself running the last half-block before he reached his own home. He burst in the door and called out with forced cheeriness, "Hi, Mom, what's cooking? I'm starved. The whole gang's coming over in a few minutes. I hope you've got something for them." His mother came out of the kitchen, her face gray with uncertainty. "You'll have to do with sandwiches this afternoon," she said. "I haven't been able to use the electric stove since noon." Ken stared at