from the site:A 60 rpm (revolutions per minute) motor drives the entire mechanism. It rotates once every second. The following pulley rotates once every 5 seconds (1:5 ratio). The next rotates once every 60 seconds or 1 minute. Then 5 minutes, 1 hour, 1 day, 1 month, 1 year, and 1 decade. The decade wheel carries the load of the large arc. The large arc rotates once every century. The final ratio between the 60 rpm motor and the large arc is approximately 1:31.6 billion.
Each wheel is marked with a black nut to highlight a position that could be tracked over time. Along the arc, 100 lines mark the divisions of each passing year. When the clock finally reaches the end of a 100 year cycle, the arc falls off its track onto the floor.