American frequency control clock, 1930s

Overview

Warren Telechron Inc. was owned and operated by Henry Warren, an important figure in early twentieth-century American horology, who patented the self-starting synchronous motor in 1916. The ‘Type A’ clock was developed to encourage power plant operators to control the frequency of their turbines, using the reliable timekeeping of a pendulum clock as a means of monitoring the speed of the mains: the bottom dial is a standard clock driven by a mechanical controlling clock. The central dial has two superimposed hands – a black hand driven by the mechanical movement, and a gold hand driven by a synchronous motor. The upper dial is driven by a second synchronous motor and can be used as a backup if the main motor fails. The ‘Type A’ was first introduced in 1916 and produced throughout the 1920s, before gradually being replaced by cheaper alternatives in the 1930s. This is one of three frequency control clocks in the collection at The Clockworks, but the only one from America, where – in contrast to the UK – the turbines turn at 60 cycles per second.