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    Re: Reaching the pole. (was Nautical Almanac)
    From: Robert Eno
    Date: 2002 Jul 4, 21:08 -0400

    George Huxtable wrote:
    
    ------clipped---------
    
    
    > I have yesterday discovered a remarkable book by Peter Ifland (occasional
    > contributor to this list) entitled "Taking the Stars", about the
    > instruments used in navigation. Superbly illustrated and very
    > knowledgeable, it has the best information I have found anywhere about
    > artificial horizons. Now I must search for my own copy.
    >
    > =========================
    Eno responds:
    
    I was given a copy of that book for Christmas a few years ago. It the
    sextantophile's (is that a word??) bible.
    
    George Huxtable wrote:
    
    > My guess is that the vibration of Fuchs' tractors upset the operation of
    > the compasses when the horizontal magnetic force was low, even if they
    were
    > well compensated for deviation (which I doubt). I have come across a
    > compass installation on a boat in which, even in UK waters, the compass
    > card would rotate anticlockwise, slowly and continually, whenever the
    > engine was running.
    
    Eno responds
    
    It appears that we have similar tastes in reading material. I have a copy of
    Fuchs' book: "The Crossing of Antarctica" which I have not read for fifteen
    years. I have also read Hillary's account, the name of which, unfortunately,
    escapes me at the moment. Both Fuchs and Hillary used a sun or astro compass
    on their respective journeys. Fuchs refers to a "sun compass" and I seem to
    remember seeing a photo in Hillary's book, of an astro-compass mounted on
    one of the converted farm tractors, which he used on his end.
    
    Interestingly enough, at least from the material that I have read, there was
    a bit of friction between Hillary and Fuchs. There's the old strong-willed
    polar explorer characteristic again!
    
    It always puzzled me how they were able to make use of the sun or
    astro-compass to maintain a heading. I've never used a device called a "sun
    compass", however, I am intimately familiar with the astro-compass, which
    has to be levelled with two built-in spirit levels, in order to obtain an
    accurate heading. Perhaps they stopped every once in a while, levelled their
    astro-compasses and took a heading off of a distant object.
    
    George Huxtable wrote:
    
    It's a pity that Amundsen doesn't supply any details
    about
    > these aspects of the navigation. An important reason for precise
    navigation
    > was the need to locate depots of food and equipment where these had been
    > left beforehand, and marked by snow-cairns and flags.
    
    Eno responds:
    
    Yes, it is a great pity. Amundsen supplied so many minute details about the
    planning, preparation and execution of his expedition but is laconic where
    navigation is concerned. Perhaps he felt that this was too obtuse a topic to
    relate in a book intended for the general public.
    
    Amundsen's method of finding his cairns was not just a matter of hitting the
    depot dead on. He took the time and trouble to mark the depots by placing
    colour coded flags, mounted on bamboo poles, a considerable distance east
    and west of each depot. In this way, he did not have to find the needle in
    the haystack, he only had to locate one of the colour-coded flags which
    would lead him right to the depot. In otherwords he created a target about
    two miles wide (can't remember the exact distance that he spread out his
    flags) which is far easier to find than a single snow cairn. Yet another
    example of Amundsen's brilliant planning and forethought.  The guy was truly
    a professional. Admittedly, I am very biased. Amundsen is one of my heroes.
    
    
    Robert
    
    
    

       
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