Around 1830, a Liverpool watchmaker-enamelist had the novel idea of emptying the upper half of the dial of a common gusset watch, in the shape of a half-moon or sector, and adding a glazed disc below with two scenes at erotic character anchored in the hour axis, so that the gusset watch represents a different position every six hours.
They were very successful, and a large number of gusset watches of these features were handcrafted, all of which are different and are currently highly prized by collectors and museums.
