In a corridor of the physics building stands a glass funnel of black pitch. It looks like a hard black stone, but it flows, so slowly that a drop forms and falls only about once every eight years. Professor Okafor, who was seventy-one, had watched it for forty years. Five drops had fallen in that time, and he had missed every one: one at lunch, one at the dentist, one on the only night he went home sick.
The sixth drop was hanging at the end of the funnel, long and thin. Okafor was retiring at the end of the month. His granddaughter Wen, thirteen, came to stay and sat on a stool with a thermos, watching the funnel. Her grandfather fell asleep on the corridor sofa.
At twelve minutes past three the thread stretched, thinned and fell with a soft plop into the glass below. She had seen it! She shook her grandfather. "Grandpa. It fell."
He looked at the empty end and the new drop in the beaker. "Tell me what it looked like." She told him. He wrote in the logbook: "Drop six. 3:12 a.m. Seen by Wen, aged thirteen."
