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    Re: Lewis & Clark's artificial horizons
    From: Greg B
    Date: 2014 Jan 02, 10:12 -0500
    Hi Guys,
            Yes, I have read about the three artificial horizons in various documents and on websites.
    I also read their inventory - and nowhere did I see a reflecting circle, or similar instrument.
    So I ask the list: how did they deal with the large (2X) angles caused by using a artificial
    horizon - particularly during late spring & summer with the additional tilt? Did they only
    do Lat by Polaris? Any incites?
    Thanks,
          ~Greg
     


    On 01/01/2014 08:43 PM, Bruce Stark wrote:

    Greg Licfi apparently has read Lewis's description of his three artificial horizons and knows he doesn't have to deal with mercury for his reenactment. Lewis and Clark only had the two mirror horizons provided by Patterson and a water horizon made by Ellicott.

    The water horizon generally pictured is the one that was in Ellicott's kit when he surveyed the US - Spanish line from the Mississippi River to the Atlantic Ocean. The L&C expedition had a different, improved version. In a letter to President Jefferson, answering the request that he teach Lewis how to find latitude and longitude, Ellicott wrote that twenty year's experience had taught him to prefer water -- in spite of its limitations -- to any other form of artificial horizon. And he mentions his improvement to the standard model. Since the cover didn't touch the water pan, the water didn't tremble with every puff of air that shook the cover. My folding version of this horizon worked just fine when it was blowing so hard the camp-chair went over as soon as I got out of it.

    Patterson's mirror horizons are interesting, and were only a slight addition to the load of unnecessary embellishments that were laid on Lewis, and stood in the way of his understanding what was essential.

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