[time-nuts] How did they distribute time in the old days?

Bill Hawkins bill at iaxs.net
Wed Oct 14 14:05:31 EDT 2015


The book "Einstein's Clocks, Poincare's Maps" describes a pneumatic time
sync method for the public clocks on poles in the city of Paris, France
in the late 1800s. Pneumatic clocks were made and used in the US for a
while. Got one from the four letter auction site and dreamed of making a
pneumatic pulse generator synched to 10 MHz. Sadly, the diaphragm in the
pneumatic mechanism had rotted away, so I gave the clock to a friend who
could make it work, but didn't. One pulse advanced the clock one minute.
There was no auxiliary clockwork to keep it running between hourly sync
pulses.

I don't know of any mechanical clocks that sync once a day. IIRC,
Western Union had to send people to advance or retard the hour hand when
daylight savings time became common.

There is something about those clocks that makes a time nut want to
restore one.

Bill Hawkins


-----Original Message-----
From: Nick Sayer via time-nuts
Sent: Wednesday, October 14, 2015 11:42 AM

The WU standard time service goes back further than the turn of the 20th
century. It started in 1870.

I've always wanted to get my hands on one of those clocks and come up
with a circuit to recreate the synchronization signal for it, probably
with a Raspberry Pi running ntpd and a big ol' MOSFET. The problem is
that at this point, those clocks are quite expensive once they're
reconditioned.

My understanding (perhaps incorrect) was that the sync pulse was once
daily and, as you said, would cause the hands to "snap" to 12. The
trailing edge of the pulse was synchronized and would release the clock
to operate normally.

That they had something as accurate and widespread as it was so early is
astonishing.



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