This clock tells  time by revealing the hour and then the 5 minute interval after past the hour. This is a participatory clock and it's activated when it detects a weakly magnetic sphere dropping into the hole at the top of the case. When the marble reaches the bottom of the entry tube it's "grabbed" by a magnet on a linear actuator that is hidden by a sheet of wood. The linear actuator drags the marble to a position under one of 12 numbers that corresponds to the hour of the day. After a brief pause the sphere is dragged to the extreme right where gravity causes it to separate from the magnet. The sphere drops to the lower level of the track where it's "grabbed" by a second magnet attached to the linear actuator. Now the actuator positions the sphere opposite the number corresponding to the correct minute interval after the hour. After a pause the sphere is dragged to the extreme left where again gravity causes it to be release by the magnet and it drops down the tube and out of the clock for reuse.