This striking electric mantel clock was made by Bulle, probably relatively early in the company’s long career: the four-glass bronzed model can be found in a company catalogue of 1925, while the patent for electric striking dates from 1923. The principle of Bulle clocks is the electromagnetic solenoid used as a pendulum bob. This swings back and forth over a stationary, curved magnetic bar. Near the top of the pendulum is a silver pin, which makes contact alternately with the two sides of a pivoted fork as the pendulum swings back and forth. One arm of the fork is insulated while the other acts as a conductor, allowing the circuit to be made and current to flow to the drive coil of the bob. An isochronal spring is fitted to the pendulum rod to attempt to correct for circular error. A skeletonised dial makes it possible to see Bulle’s distinctive ‘walking pawl’ escapement in action, which is activated by the side-to-side motion of the fork. An isochronal spring is fitted to the pendulum rod to attempt to correct for circular error. Bulle produced many thousands of clocks for well-heeled domestic markets during the early twentieth century, capitalising on their own research and innovation with battery technology at a time before mains power was sufficiently reliable for widespread domestic use.
