May 29, 2002
Take an empty thread spool, lace a thin piece of string about a foot long through the hole, and thumbtack the ends of the string to the top frame outside of a windowsill to a house. On a windy day, the spool will swing to and fro; tapping at the window, giving the impression that someone is at the window tapping the glass. It is most effective on gloomy stormy nights or Halloween when there's a wind. It's most effective if it's secure away from view so that the person inside doesn't see it and thinks it's a ghostly tap.