Clock features a peek-a-boo dial

In the early 19th century clock makers started using brass movements  that ran for 8 days .  In order to display that their clock had one of these movements and not one of the old wood movements they put in a viewing hole.   below the 12 o'clock position is a crescent shape design opening with a small looking glass.  A rod behind the top decoration is lifted to pull up mirror to show off the modern brass movement.   This way you knew you were getting the latest in technology!