How does a cuckoo clock cuckoo?

The "cuc-koo" sound is created by two tiny gedackt (pipes) in the clock, with bellows attached to their tops. The clock's movement activates the bellows to send a puff of air into each pipe alternately when the clock strikes.

Gedackt (also spelled gedeckt) is the name of a family of stops in pipe organ building. They are one of the most common types of organ flue pipe. The name is a German word, meaning "capped" or "covered".






Both from en.wikipedia.com under Cuckoo Clock and Gedackt, respectively, accessed 1/26/2011.

Picture also from wikipedia, posted by Leeawiki on March 20, 2007.