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    Re: Longitude by altitudes. was Re: How Many Chronometers?
    From: Gary LaPook
    Date: 2009 Sep 22, 03:41 -0700

    The same can be done with any cheap digital watch with a stopwatch 
    function. They allow you to take many "lap" times just by pushing a 
    button which you can read later. Reset the stopwatch and then start it 
    running and write down the clock time. Then just press the "lap" button 
    for each shot. At the end of all the shots simply recall the "lap times" 
    from the memory and add them to the start time to establish the times of 
    the shots.
    
    gl
    
    
    
    Brad Morris wrote:
    > And speaking of navigation and time....
    >
    > For a very long time, I was puzzled by Dutton's recommendation to navigators 
    that they obtain a split seconds watch.  He described two second hands.  One 
    would continue to beat time, the other would pause and hold the time whilst 
    it was recorded.  I search far and wide for a "split seconds" watch of this 
    type.  I am very pleased to report to the list that such a watch should have 
    the complication known as "rattrapante".  When you search on eBay for this 
    type of watch, you immediately get listings describing exactly what Dutton 
    recommended.
    >
    > I somehow managed to obtain one.  Am I ever pleased!  The rattrapante 
    chronograph I obtained holds not only the seconds, but the hours and minutes 
    and tenths of a second as well. All of the hands are analog.  I have set the 
    rattrapante complication to GMT, while the normal analog watch is set to my 
    local time zone. Upon observation, I reach with my left hand to my right 
    wrist and press the button.  Now the altitude and time correspond and can be 
    recorded at leisure.
    >
    > I have been carefully rating the rattrapante against the USNO time, 
    (202)-762-1069 here in the US.  The rate is 0.200 seconds per day, when rated 
    over the past 20 days.  Each day, the USNO time is compared to the 
    rattrapante, and the resultant error is recorded.  Since the tenths of a 
    second is the resolution, I should continue more than 50 days to eliminate 
    any quantizing error. If the rate is not precisely 0.2 seconds, then as the 
    accumulation of short or long rate continues, eventually, there will be an 
    advance or retreat that holds.
    >
    > I thought it relevant to report the name to others who might wish to obtain 
    the watch recommended by the US Navy for celestial navigation.  Dutton, after 
    all, was the text used at the Academy!
    >
    > Best Regards
    > Brad
    >
    >
    >
    >
    > -----Original Message-----
    > From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of frankreed@HistoricalAtlas.com
    > Sent: Thursday, May 14, 2009 9:56 AM
    > To: NavList@fer3.com
    > Subject: [NavList 8259] Re: Longitude by altitudes. was [NavList 8178] Re: How Many Chronometers?
    >
    >
    > Peter, you wrote:
    > "Speaking of straw-man arguments..  This would seem to be an irrelevant 
    distraction, Frank, introduced to cloud the issue."
    >
    > And you wrote:
    > "Frank, your central argument is parading itself about in public while 
    wearing no clothes.  It is not a good look.  Be a good chap and cover 
    yourself up"
    >
    > And you wrote:
    > "Do you just make up this stuff as you go along?"
    >
    > And you wrote:
    > "similar opinions to yours with no basis at all for their suppositions (and 
    that were, incidentally, self-serving, just like yours)."
    >
    > Thanks, Peter. Fascinating points, as always.
    >
    > -FER
    >
    >
    >
    >
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    > >
    >
    >   
    
    
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