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Re: Speaking of time service

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On 2020-09-11, JimP <chucktheouch@gmail.com> wrote:
> On Fri, 11 Sep 2020 19:10:28 GMT, usenet@only.tnx (Questor) wrote:
>>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:
>>>>
>>>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.
>
> I remember we deliberately steered well south of our home port. That
> way the bridge personnel knew they just had to turn north when we
> picked up the U.S. on radar.
>

Sailing ships, I believe, would take soundings and reduce speed 
when they got them, either going west or east. 

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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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