MACHINERY
'(<a href="http://www.j-archive.com/media/2006-05-18_J_30.wmv">Cheryl of the Clue Crew holds a ticking metronome.</a>)  This mechanism that provides periodic energy to devices like a metronome gets its name from the <a href="http://www.j-archive.com/media/2006-05-18_J_30.jpg" target="_blank">wheel</a> that is caught & then gets free'
an escapement