Preston tuners

Preston tuners or machines (also known as peacock, fan, or watchkey tuners) is a type of machine head tuning system for string instruments, named for English cittern (English guitar) maker John Preston and developed in the 18th century. Preston claimed to be the inventor of this design, though scholars note the originator could be the luthier John Frederick Hintz, who advertised such a mechanism as early as 1766. The tuning mechanism was also used on the German cittern known as the waldzither, and is associated with the early 20th century instruments built by C. H. Böhm.