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

[Brian Inglis]

On 2015-10-14 10:42, 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.

Ingenuity was never lacking - a few quotes from
https://archive.org/details/GreenwichTime - well researched and still
available in a later edition - includes many incidents which I found
humorous - the first ilustrating that TWTT long predated Cs clocks:

""Difference of longitude can be determined astronomically or geodesically (by
trigonometrical-survey methods) or, as we have seen, by the transport of
chronometers. One of the earliest examples of the use of this last method took
place during the geodetic operation to connect Paris and Greenwich
Observatories in 1784-8, instigated by Cassini de Thury and conducted on the
English side of the Channel by Major-General William Roy, FRS. In September
1785 Maskelyne sent his assistant Joseph Lindley by post-chaise and
cross-channel packet to Paris and back carrying eight of John Arnold's
chronometers, yielding a difference of longitude of 9 minutes 19.8 seconds,
only about a second too small and agreeing well with the existing astronomical
determinations and the geodetic result. 1 In 1825 a series of rockets was used
by John Herschel and Col. Sabine to connect Paris and Greenwich. The
chronometer method continued to be used for longitude determination of
observatories until the coming of the electric telegraph. For example, in 1843
more than sixty chronometers were sent sixteen times backwards and forwards
between Altona near Hamburg and Pulkowa near today's Leningrad, and the
following year forty chronometers went the same number of times between Altona
and Greenwich. Chronometers were sent across the Atlantic many times to
determine the longitude difference between Harvard and Liverpool Observatories,
from which the difference of longitude between Harvard and Greenwich was
accurately determined. In 1844 the longitude of Valentia Island and the west
coast of Ireland was found in this way, under Airy's superintendence."

"The use of the electric telegraph for this purpose was first suggested by the
American astronomer S. C. Walker and first used in the USA about 1849. As we
have seen, the telegraphic connections between Greenwich and the Continent were
suggested by Airy in 1851, connection with Brussels being established in 1853,
and with Paris in 1854. The longitude of Valentia was redetermined by telegraph
in 1862."

"The first successful submarine cable was laid across the English Channel in
1851. Wales and Scotland were linked with Ireland in 1852, England with Belgium
and Denmark in 1853. By 1860 London was connected with the Indian subcontinent,
one of the longest submarine cables being between Malta and Alexandria, 1,565
miles. But the really exciting prospect was a cable - perhaps more than one
-between Europe and North America. Its main protagonist was the great American
Cyrus W. Field (1819-92), whose untiring efforts provided the impetus
throughout."

"The next year, however, a new cable was successfully laid by the Great Eastern,
taking fourteen days from Valentia to Heart's Content in Newfoundland. To
complete the triumph, the Great Eastern successfully grappled the 1865 cable,
spliced it on to cable remaining on board, and thus provided a second cable
link across the Atlantic.

One of the factors leading to this success was that during the 1866 lay, at the
suggestion of Captain Anderson, the Greenwich time signal was received by the
Great Eastern twice daily by telegraph via London, Holyhead, Dublin, Valentia,
and the cable she was laying, thus enabling her to find her longitude exactly.
This seems to be the earliest example of a ship at sea receiving a time signal
by other than visual means. One of the earliest uses of the new cable was to
redetermine the longitude difference between the observatories of Greenwich and
Harvard University at Cambridge, Mass. This was conducted in October 1866 by Dr
B. A. Gould of the US Coast Survey, in co-operation with Airy."

-- 
Take care. Thanks, Brian Inglis