"Don't!" Angus Haney screamed, and rolled clear of me. He was on his feet in an instant and wrestling to get the pipe from my companion. "If I destroy it, you fool," the man who hadn't been born yet said, "I won't build my own version of it and won't be trapped back here in your twentieth century. You can't stop me." But Angus, who outweighed his antagonist, had other ideas. In the brief time it took me to climb to my feet and reach them, the metal pipe went clattering away across the floor and Angus was wrestling his relative away from the time machine. I grabbed Angus' shoulder and swung him around and hit him. He dropped like a stone and, with a whoop of triumph, my companion scrambled after the heavy metal pipe. Angus was down but not out. I'll have to say this for him; he had guts. He was on his feet again before Great-great could reach the machine. I'll never forget that scene. For a moment time seemed to be suspended. Great-great stood poised with the metal pipe at the top of its arc, ready to bring it down with crushing force on the delicate control bank of the machine. Angus seemed to stop in mid-air as he leaped for the pipe. Immediately behind him was the glass-enclosed booth of the machine. Or--and this is important--it was glass-enclosed on three sides. The fourth side was nothing but air. I caught Angus around the waist and pulled him back. We stumbled away from the machine and then back toward it. Suddenly Angus went limp. It was the oldest trick in the book, but I fell for it. I relaxed my hold on him and, as soon as I did, he became a fury. Something struck the side of my head and the next thing I knew I was staggering toward the time machine. Just as Great-great brought the heavy metal pipe down. I staggered inside the glass-enclosed booth. There was a loud crashing sound. And then--unexpectedly--a faint hum--a sudden blurry curtain before my eyes--a rolling, seething, billowing mist of white--and a moment of exquisite pain.... And Angus Haney's voice from a million miles away: "You're destroying it...." Then blackness like the gulf between the stars. Or between the centuries. * * * * * Well that's the story. I'm telling you everything so you'll understand. I am not--repeat, not--crazy. I'm as sane as you are. Of course my emotional responses to your mental tests are different: I'm from the twentieth century. I know I can't get back. I know a little more ought to be said about my story. Angus failed to stop Great-great, who completely demolished his machine. How do I know? Because you never even heard of a successful experiment in time travel here in the twenty-first century. Simple, isn't it. I wish I knew Great-great's name. If I knew his name and could find him, he'd confirm my story. I know what you're thinking. Believe me, I am not a paranoid. I....