Synchronome - Two Pendulum Electric Clock

Synchronome clocks were first made in 1900. They were known for their accuracy. The basic design called for a swinging pendulum to receive a boost of electricity, thus preventing the decay of the swing. Not only were they accurate but they were designed as master clocks. The central clock could control the time shown on clock faces in many remote locations. They were commonly used in schools and factories.

In 1921, William Hamilton Shortt, the director of the company, invented a new form of pendulum clock that used two pendulums in synchrony to measure time (Patent Number 187814). The master clock's pendulum was encased in a vacuum tube to reduce drag. It delivered an electric pulse to the pendulum of a second clock that corrected the swing much more accurately. The clocks were accurate to a millisecond per day. If you are interested in the mechanics of clocks, J E Bosschieter has great animations showing the workings of the clock. Choose your language by clicking a flag and then go to Page 10. You will need the Shockwave plug-in to view them.

Only about 100 of the clocks were made and they were used primarily in observatories around the world. The clocks improved the accuracy of measurement in astronomy and were used into the 1950s when they were replaced with atomic clocks.

This Synchronome housed at the Beijing Ancient Observatory (古观象台) includes a second hand and a 24 hour dial.
Last update: September 2007
© Marilyn Shea, 2007