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    Re: Lindbergh-Weems Second-Setting Watch -- Notes on Design and Use
    From: Brad Morris
    Date: 2018 Nov 26, 15:57 -0500
    Hello Ed

    Thank you for your kind words.  The only thing I did was to help you to organize your thoughts.  You did all the heavy lifting!

    I still want one of these watches, now that I understand how they work.  Really a very nice way to get apparent time at sea, although Longines oversold the watch when Longines said it would provide your longitude*.  Yes, it will, but only after a bit of sextant work, and not directly.


    *See Longines advertisement in Ed's paper.

    On Mon, Nov 26, 2018, 12:05 PM Ed Popko <NoReply_EdPopko@fer3.com wrote:

    I received enough questions about the Lindbergh-Weems Second-Setting navigation watch that I decided to consolidate my notes and PostScript simulator output into a short paper. Attached is an overview of the watch's various dial features and examples of how to use the hour/minute/second hands to calculate the sun’s Greenwich Hour Angle from Greenwich Mean Time.

    This 1930's watch from the Golden Era of Aviation is the first true pilot’s watch specifically designed for celestial navigation. All modern pilot watches owe something to this one. Longines company still manufacturers it; a modernized version is part of their Heritage line of watches.

    I would like to recognize Brad Morris for his encouragement and comments while preparing this paper. His input greatly improved the paper’s clarity and accuracy. Stan Klein did a great job of proofing and cross checking the final test. Thanks to both of them.
    NavList posts by Gary LaPook and Paul Dolkas started the Lindbergh-Weems watch discussion (see the Bibliography for specific references). Their threads inspired me to look closer and write a PostScript simulator to study how the watch works. I want to thank them for the head start they gave me.

    Ed Popko

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