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    Re: Reaching the pole. (was Nautical Almanac)
    From: Trevor Kenchington
    Date: 2002 Jul 4, 10:04 -0300

    George Huxtable wrote:
    
    > Amundsen took with him to Antarctica one Mercury horizon
    > and two Norwegian glass ones, which presumably were used with sensitive
    > spirit-levels with a strong alcohol filling to avoid freezing.
    
    
    Pure ethanol freezes at -117 Celsius (again, according to CRC tables).
    Given the difficulty of getting the last water out of any alcohol, a
    real spirit level would likely freeze at a good bit higher temperature,
    (though still well below the -40 at which a mercury artificial horizon
    would become useless). I'm not sure that I would want my life depending
    on the alcohol remaining fluid under Polar conditions.
    
    Is it possible that the glass horizons used some form of suspended prism
    or mirror, with no fluid component?
    
    
    Trevor Kenchington
    
    
    --
    Trevor J. Kenchington PhD                         Gadus{at}iStar.ca
    Gadus Associates,                                 Office(902) 889-9250
    R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
    Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555
    
                         Science Serving the Fisheries
                          http://home.istar.ca/~gadus
    
    
    

       
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