I have an identical twin brother, Don, and over the years we have had much fun confusing people—especially our teachers when we were in grade school together. Don's field is biology, and for years he taught biology and general science in high schools and prep schools. He also possesses a quirk for harmless practical jokes.

One fall day I visited Don when he was teaching at the Mohonk Prep School on Lake Mohonk in New York State. The school was operated in English style, with masters and forms instead of teachers and grades. When I arrived at his school I went directly to his living quarters. He asked me if anyone had seen me, and I replied that I didn't think so. “Good,” he said, “we'll have a little fun this afternoon after the last classes meet.” He went on and said that in his up-coming general science class he would express to his kids his amazement that it took so long before the mile was run in less than four minutes, because he himself could do it in much less time than that. “Of course, the kids will not believe me,” he said. “So I will arrange a demonstration at three o'clock on the trail that runs around the lake. You will hide in some bushes back down the trail, and at the shot of a cap pistol I will take off up the trail, which runs a mile around the lake.