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by Geoff Jull

My interest in Master-Clocks as used in the older telephone exchanges for time pulses etc. led me to research reports of Master-Clocks that controlled a network of slave clocks driven by compressed air.

In the late 1870s the city of Vienna approved construction of a compressed air system designed for clocks in public spaces as well as private and commercial buildings.

Within three years over 20 miles of lead pipes were laid in the sewers, both in Vienna as well as Paris. Approximately 1000 private homes were connected as well as commercial buildings and many Pillar-Clocks with multiple dials were erected in prominent public places.

A steam engine operated air compressors to keep the reservoirs full of air at up to 45 pounds per square inch of pressure. The distributing pipes were made of lead with an internal diameter of one inch. Further branch pipes of quarter inch diameter lead into customer's houses or commercial buildings.

The central Master-Clock was a precision weight driven mechanical movement with the weights being automatically wound up by a miniature steam engine. The clockwork was connected to a slide valve mechanism similar to the steam chest and valves of a steam locomotive.

Every 60 seconds the air valve is opened for 20 seconds and compressed air is released to the pipes. In each slave clock bellows received a puff of air and the hands of the clock would be advanced in steps of one minute.

The system was never adopted in England or the USA.

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