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    Re: Longitude sight, South Pacific, 1864
    From: Brad Morris
    Date: 2018 May 16, 20:09 -0400
    Hello Charles

    Logarithms permit multiplication by addition.  That is, instead of multiplying two numbers together, we add the logarithms of those two numbers and then take the inverse logarithm to find the same result as pure multiplication!  

    Similarly, one can divide two numbers by the subtraction of logarithms of those numbers and then taking the inverse log.

    It is a far less error prone and gets rid of those pesky, "error prone" multiplication tables.  

    Slide rules are typically logarithms realized in a physical medium, if that's any help in visualizing this!


    On May 16, 2018 7:47 PM, "Charles McElhill" <NoReply_McElhill@fer3.com> wrote:

    I have a question regarding the use of logarithms. What was the advantage for 19th century navigation?

    You see this a lot in old navigation text. Was it just to simplify interpolation ?  Thanks

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