To help equalize the pull of the mainspring as it ran down, in the 15th century, watch makers created and starting using something called a “Fusee”.  These were made by cones with a chain on them and the chains helped to pull at the gears to keep the watch running smoothly.   Before these were made, springs were used to power watches and the springs would start to lose power over time.  Fusee chains compensated for the diminishing power of those springs.  The first Fusee was seen in 1525.  I have no idea at the date of the Fusee, although they were no longer used at about 1900.

This Fusee chain, has been coated in resin and placed on top of a watch calendar.  Then these were attached to a silver colored metal wing and hangs with a silver-plated bail.