A regulator is a clock with exceptional accuracy, made possible by the invention of the deadbeat escapement in 1715. Regulators were called such because they were used to regulate less accurate clocks and watches. For example, they were used in train stations and jewelry stores, where great accuracy was essential. Over time, however, less accurate clocks were labeled regulators, so eventually the term “regulator” just became a generic name for a hanging wall clock.
Seth Thomas “Regulator 6″ oak wall clock, second hand., time only, brass weight & pendulum, ca. 1905,16 X48″ h. $2,400.