Hope-Jones synchronome remontoire

Synchronome remontoire mechanism removed from the original transmitter clock installed in One Birdcage Walk when it opened in 1899.

The synchronome remontoire mechanism (also known as an electrically maintained or driven pendulum) was created by horologist Frank Hope-Jones and led to improvements in timekeeping accuracy.

The synchronome remontoire used a gravity arm reset by an electro-magnet to impulse the pendulum. This impulse would occur every 30 seconds. Hope-Jones realised that the impulse could not only drive the hands of its transmitter clock but also those of multiple receiver clocks too. This led to the Synchronome system which was installed at One Birdcage Walk. The main transmitter clock governed the time shown by all the clocks in the building. Synchronome systems could often be identified by an audible click which would occur every 30 seconds.