SteelCamel wrote:I'm pretty sure number 5 is indeed an electric clock - specifically a slave clock, which would be driven by electrical pulses from a master clock elsewhere in the building so all the clocks stay in step. They were quite common in all kinds of large buildings at one point, but as this one appears to have a drive for hands on both sides I'm guessing it's from a railway station.
"Slave clock" is the answer I was looking for. I understand that this one came from a Belgian cinema. I have the rest of the clock, someone wanted to know if I could make it work (Why me?
).The master clock would be a very accurate pendulum clock in a wooden case, often oak or, if the business owner really wanted to show off, mahogany. It would send a pulse typically every minute so all of the slave clocks (normally wired in series) would advance one full minute every minute. If you see a clock where the hands advance in one minute intervals, it is probably a slave clock.
Master clocks are so accurate that atmospheric pressure has a noticeable effect. A lower atmospheric pressure causes less drag which causes the clock to slow down. This seems counter-intuitive but, with less drag, the pendulum swings further, thus, the period is slightly greater. Leaving the door open has the same effect.
The one in the photograph requires pulses of alternating polarity. UK ones usually work ok with pulses all of the same polarity.
Julian F. G. W.
Tubeless tyre repair kit.
Half-mark for film development timer.