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

[Ralph Smith]

I drive one of my Self Winding Clock Company/Western Union clocks using the NTP server I built using a Trimble Thunderbolt and a Soekris Net4501. I use a GPIO line to drive a simple transistor switch using the same 3 volt battery that I also use do power the winder. The pulse from the GPIO pin is accurate to a sub-microsecond level. By the time you deal with the solenoid and the mechanical issues in the synchronizing arm, it is, let us say, somewhat less precise.

On a side note, I have in my possession the book “Selling the True Time: Nineteenth-Century Timekeeping in America”, <http://www.amazon.com/Selling-True-Time-Nineteenth-Century-Timekeeping/dp/0804738742/ref=sr_1_1?ie=UTF8&qid=1444919952&sr=8-1&keywords=selling+the+true+time>. Interesting read about railroads driving the need for standard time, as well as college and university astronomers setting up a cottage industry of selling the time. Western Union, with its telegraph distribution of time from the US naval observatory and using the Self Winding Clock Company clocks supplanted the local observatories.

Ralph
AB4RS

> On Oct 14, 2015, at 2:02 PM, Brooke Clarke <brooke at pacific.net> wrote:
> 
> Hi Nick:
> 
> One of my Self Winding Clock Co. (WU) clocks was taken down yesterday for painting.
> When put up one of the Ken's Clock Synchronizers was installed and the hands moved to align with the heart shaped cam it uses, but it never worked.
> The problem was it used a 4.5 Volt signal which can develop the current needed to pull the sync electromagnet the time constant is far too slow.
> I'm going to add a high voltage circuit with series resistor to get the time constant down one or two orders of magnitude.  The key to this is a PCB I make that holds 5 each 9V batteries connected in series, so I'll use one, two or more of them to get the time constant down.
> http://www.prc68.com/P/45VS.html
> 
> Before I had the 45 Volt Stick I was considering getting the needed high voltage by charging a cap a minute or two before the top of the hour and discharging it through a resistor.  Here's a video showing that would work.
> http://www.prc68.com/I/SWCC.shtml#Experiments_Feb_2014_
> 
> Mail_Attachment --
> Have Fun,
> 
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> http://www.prc68.com/I/DietNutrition.html
> Nick Sayer via time-nuts wrote:
>>> On Oct 14, 2015, at 4:42 AM, billriches <bill.riches at verizon.net> wrote:
>>> 
>>> Not milisecond time distribution but time related!
>>> 
>>> In the early half of the 1900s Western Union was in the time business.  They
>>> would rent businesses such as banks, office buildings, etc  clocks for a few
>>> dollars a month.  These were pendulum wall clocks that had 2 #6 dry cell
>>> batteries inside that would wind them every hour or so. The clocks were
>>> connected to the WU telegraph line and for a minute before and after  the
>>> top of the hour all traffic on the circuit would stop.  Exactly at the top
>>> of the hour they would push a pulse of 50 ? volts or so over the line and it
>>> would reset the clock to the top of the hour.
>> 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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