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    Re: FW: Re: Chronometer Suggestions
    From: Gary LaPook
    Date: 2009 Jan 14, 17:34 -0800
    You wrote:
    "I think it's well known that 1' of arc varies in length as a function
    (cos)
    of the latitude."

    That is true for one minute of longitude because parallels of latitude are small circles.
    This is not true for one minute latitude of for any
    other great circle. (Technically these also vary slightly due to the
    oblateness of the earth but these small variations are ignored for
     celestial navigation purposes.)

    gl



    --- On Wed, 1/14/09, Irv Haworth <irvhaworth{at}shaw.ca> wrote:
    From: Irv Haworth <irvhaworth{at}shaw.ca>
    Subject: [NavList 7052] Re: FW: [NavList 6952] Re: Chronometer Suggestions
    To: NavList@fer3.com
    Date: Wednesday, January 14, 2009, 4:25 PM

    Hello FER
    Sorry for delay in responding to your comments.We have been snowed in and my
    health (and perhaps mental..hi...hi) is not what it should be.

    O.K. If I digest your message correctly it is unclear to you what I'm
    trying
    to say (most unfortunate as English is my first and really only
    language..h.). I appreciate that my attempts at writing a good preacipe have
    failed.
    However before carrying forth , I would appreciate it if you would tell me ,
    exactly what is not clear. (I find it hard to believe that you are
    questioning the note about mass varying with latitude or that the length of
    1 NM (admittedly I had tongue in check when I presented it to several
    decimal places) or that 1' of arc on a GC is = 1 NM or about Marc
    St.Hilaire
    and the intercept technique.
    I think it's well known that 1' of arc varies in length as a function
    (cos)
    of the latitude on say the earth so that to me leaves to believe the
    problem lies with how does one plot his position on (a) a sphere (globe)
    (b) on a Mercator chart.
    Given the above I would be most appreciative if you would spell out, in
    specific / definitive terms where you believe my statements are without
    foundation.
    Kind regards;

    Irvin Francis Haworth
    L 49° 20.895' N
    λ 123° 08.617 'W


    -----Original Message-----
    From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf
    Of frankreed{at}HistoricalAtlas.com
    Sent: January 10, 2009 4:29 AM
    To: NavList@fer3.com
    Subject: [NavList 6973] Re: FW: [NavList 6952] Re: Chronometer Suggestions


    Irv H., you wrote:
    "I don't think this forum was intended to be used as a teaching
    platform "

    Who told you that?? There are plenty of opportunities to teach here.

    That said... ahem.

    Look, Irv, I've re-read this last post from you three times, and I have to
    tell you, I can't figure out what you're trying to say. And of the few
    claims you appear to be making, several seem flat-out wrong. I would invite
    you to clarify your points. Don't mince words. Spell it out in detail so we
    can make sense of what you're saying...

    -FER









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