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Re: Speaking of time service

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On Thu, 10 Sep 2020 15:05:27 -0500, JimP <chucktheouch@gmail.com> wrote:
>On Thu, 10 Sep 2020 11:52:12 -0700 (PDT), hancock4@bbs.cpcn.com wrote:
>>On Thursday, September 10, 2020 at 2:24:48 PM UTC-4, Chris wrote:
>>
>>> The IBM clocks, with a Graham escapement, were quite accurate
>>> to start. There were several models, but the standard model
>>> was rated at 15 seconds / month, electrically wound spring,
>>> and a more accurate weight driven model at 10 secs / month.
>>> I rebuilt one of the standard models and got it rated to better
>>> than 20 seconds in 3 months. Bit more effort may have done
>>> even better. Not bad for a purely mechanical design...
>>
>>Better than my Casio watch.
>>
>>The care and feeding of old time mechanical devices amazes
>>me.  For instance there used to be a popular railroad
>>worker watch, Hamilton.  Supposedly very durable and
>>accurate. Expensive to buy Yet periodically they needed 
>>inspection and service by a trained watchmaker (railroads had
>>such men on the payroll for that reason).
>>
>>My cheap electronic watches only need a battery 
>>periodically. Generally keep very good time.
>
>We had mechanical clocks aboard ship. Once a week one of the
>quartermasters, not supply but kept the ship's log and wound these
>chronometers, would stop by our office and check the time on it.
>
>He had a mechanical pocket watch, he told me it was also a
>chronometer. The Executive Officer and the head quartermaster would
>take noon sightings of the sun and adjust that pocket chronometer once
>a week.

Sighting the sun can give you your latitude -- but you have to know when it's
(solar) noon.  (Otherwise you need to make a series of sightings around
estimated noon and pick the one of greatest extent.)  But time and longitude are
linked. You can get one if you know the other, but if you don't know either then
you're lost.  This was a big problem until a solution was found for accurate
timekeeping at sea.  The usual means of the day -- water clocks, pendulum
clocks, et. al. -- got screwed up by the ship's motion at sea.  The story is
recounted in Dava Sobel's book, "Longitude," also the basis for a PBS NOVA
episode.

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Speaking of time service hancock4@bbs.cpcn.com - 2020-09-10 11:09 -0700
  Re: Speaking of time service Chris <xxx.syseng.yyy@gfsys.co.uk> - 2020-09-10 19:24 +0100
    Re: Speaking of time service hancock4@bbs.cpcn.com - 2020-09-10 11:52 -0700
      Re: Speaking of time service JimP <chucktheouch@gmail.com> - 2020-09-10 15:05 -0500
        Re: Speaking of time service Chris <xxx.syseng.yyy@gfsys.co.uk> - 2020-09-10 23:29 +0100
          Re: Speaking of time service gareth evans <headstone255@yahoo.com> - 2020-09-11 19:18 +0100
          Re: Speaking of time service hancock4@bbs.cpcn.com - 2020-09-11 11:42 -0700
            Re: Speaking of time service JimP <chucktheouch@gmail.com> - 2020-09-11 15:24 -0500
        Re: Speaking of time service Peter Flass <peter_flass@yahoo.com> - 2020-09-10 16:12 -0700
          Re: Speaking of time service J. Clarke <jclarke.873638@gmail.com> - 2020-09-10 19:40 -0400
            Re: Speaking of time service JimP <chucktheouch@gmail.com> - 2020-09-11 09:14 -0500
          Re: Speaking of time service JimP <chucktheouch@gmail.com> - 2020-09-11 09:10 -0500
        Re: Speaking of time service hancock4@bbs.cpcn.com - 2020-09-11 11:45 -0700
        Re: Speaking of time service usenet@only.tnx (Questor) - 2020-09-11 19:10 +0000
          Re: Speaking of time service JimP <chucktheouch@gmail.com> - 2020-09-11 15:26 -0500
            Re: Speaking of time service Peter Flass <peter_flass@yahoo.com> - 2020-09-11 16:21 -0700
            Re: Speaking of time service maus <maus@dmaus.org> - 2020-09-12 12:36 +0000
      Re: Speaking of time service Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-09-10 23:34 +0000

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