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    Re: Alternate methods of sight reduction
    From: Peter Fogg
    Date: 2005 Dec 7, 08:20 +1100

    There certainly were a lot of old-fashioned methods, Jim. Tables were useful to allow computation of the navigational triangle, and apparently some List members still prefer to use a slide rule, possibly because they are familiar with it and it gives a result appropriate for their needs.

    However, a few decades ago the small, inexpensive electronic calculator was introduced. With it and appropriate formulas a precise result can be quickly and directly produced. Tables and slide rules still have the advantage of not needing batteries, as well as being less liable to the corrosive effects of on-board life.

    Having said that, there is a lot of interest on the List in the history of navigational methods and instruments, and in the past various books, websites, etc have come up for mention. Thus there is a wealth of information within the archives of the List, apart from whatever responses you may get directly.

     

    Happy hunting

     


    From: Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM] On Behalf Of Jim Hickey
    Sent: Wednesday, 7 December 2005 7:47 AM
    To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
    Subject: Alternate methods of sight reduction

     

    Alternate methods of sight reduction

     

    First, allow me to introduce myself as a new member. My name is Jim Hickey.  My wife Judy and I currently live aboard our sailboat in St. Augustine, Florida. I have been interested in celestial navigation for many years much to the amusement and entertainment of my wife! Even got the programming bug early on but have it under reasonable control at this time. It has been a delight to read many of the fascinating postings for some time now.

     

    I have a volume of Bowditch that discusses a variety of sight reduction methods. I believe all the old table methods and more have been discussed. Has anyone had access to or knowledge of the old slide rule type method that is referenced? I believe the instrument was called a Bygrave computer which looked cylindrical.

     

    As well, there is also a picture of a wonderfully elegant looking globe like device that is set up with sliding arms that solves the navigational triangle directly.

     

    I have been intrigued by these items for years and of course would love to mess with them if I had the chance as I am sure many here would.

     

    Very curious to know how effective these approaches were and if there are others etc. etc.

     

    Cheers,

     

    Jim

       
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