[time-nuts] pneumatically synchronized clocks

[Bill Hawkins]

That's good data on the pulse time, Marc. I suppose a one-second pulse
would be severely attenuated by a kilometer of pipe.

Interesting that the first image, Air17, shows a clock at 1:50. This is
now universal for watch and clock advertising, for analog dials.

Bought the Hahl clock on eBay (thanks, Russell). The bellows has
deteriorated, but I have some experience with player pianos. Looking
forward to seeing what it needs. Also have an 1879 print from Scientific
American coming that shows the workings of a pneumatic clock.

Bill Hawkins 


-----Original Message-----
From: Marc Bury
Sent: Thursday, March 12, 2009 2:04 AM

Some more details from the pneumatic clocks in Paris in 1880:
(Sorry for the g00gle-style translation)

In "Le Magasin Pittoresque" in 1880, we can read an article entitled
"Unification of time on the electricity and compressed air".

Regarding the pneumatic clocks, we read "... Already clocks operating
with this new system, invented by Mr. Popp from Vienna, have been
installed in Paris ... 
A central clock is setup so that whenever the pendulum hits the sixtieth
second of a minute, there is a trigger switch that delivers the
compressed air in containers, it rushes immediately into the tubes of
the network, and inflate a bellows which is at their end. By blowing,
the bellows raises a small lever that rotates one step in a wheel that
has sixty, and each corresponding to one minute. At the same wheel is
set the minute hand Dial moving a minute ...
The installation of the first fifteen dials required eighteen kilometers
of pipes, and their establishment is such that all the people who live
near the pipeline network that can receive time at home. It is
sufficient to hook a small diversion conduct on the central pipe that
brings home the compressed air provided by the administration. "

In another part, I read that the pressure pulse is maintained during the
21 first seconds of each minute.

Also I found a couple of pictures from such public clocks installed in
the streets.
http://www.casimages.com/img.php?i=090312075720411213302119.jpg
http://www.casimages.com/img.php?i=090312075720411213302120.jpg

-Marc-