The Genius of Mechanical Time
Since I was a kid I have always been fascinated by these clockwork mechanisms.
There are other types of pendulums and escapements, maybe less important historically but still ingenious and fascinating.
I have right here the movement of an electric clock which I reckon received a negative pulse and then a positive pulse making one cycle per second. I have no idea where it came from but I imagine maybe they were installed in buildings where they wanted all clocks to be in sync. If the master signal ran a bit fast they could disconnect a few pulses. if it ran slow they could add them. And that would keep all clocks in sync. It is the only thing I can think of. Also, one single very precise time base could be cheaper than one per clock.
The clock has a permanent magnet and armature and at the bottom through a hole you can see the "rotor" which only rotates a minimal angle, back and forth with each positive then negative pulse.
It is interesting to see how everything is adjustable. The travel of each part etc. They compensated for low precision in manufacturing with making everything adjustable.
I have spent my entire adult life immersed in horology, and I agree that it is fascinating. Horological science is a surprisingly complex subject, and papers exploring the fine details of pendulum behaviour are still being written to this day. There are close analogies with electrical and electronic oscillators.
The slave clock you describe is exactly as you supposed. Installations had a master clock - invariably a precision pendulum clock* - which sent electrical impulses around the building to all the slave clocks. Some systems - such as Pulsynetic, Synchronome and Magenta, used unidirectional current pulses (30s for the first two, Magenta used minute pulses, IIRC). Other systems used alternating polarity pulses - IBM, for instance.
Every electromechanical telephone exchange in the UK had one or more electrically-driven pendulum master clocks which, as well as driving the slave clocks around the building - provided 1 second, 6 second, and thirty second pulses for various timing functions required by the exchange itself.
Anyway, I'd better stop or this will become a "wall of text". 😄
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* From the 1960s onwards some of the pendulum master clocks were replaced with electronic equivalents.
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