The Drop Nobody Saw

In a university corridor there is a glass funnel of black pitch. Once in eight years, one drop falls. Professor Okafor is seventy-one. He has watched the funnel for forty years. He has missed every drop! His granddaughter Wen is thirteen. She stays the night with a thermos. The professor falls asleep. At twelve minutes past three, the drop falls. Wen sees it! "Grandpa, it fell." He writes: "Seen by Wen."