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    Re: Help - Unknown Compass Graduation Arrangement
    From: Nicol�s de Hilster
    Date: 2009 Oct 23, 09:58 +0200

    Joe Schultz wrote:
    > To complete the picture, British artillery developed the "grad," or 400 
    divisions in a circle.  If you have a trig calculator then you can probably 
    do trigonometry in grads, degrees or radians.
    Actually, the 400 grad system was developed by the French as a result of 
    the quest for the metre. The 400 grad system would have been introduced 
    for all angular measurements, even those used for latitude and 
    longitude. The advantage is evident: the Paris' meridian was to be 
    divided in 40,000,000 metres and with 400 grads in a circle each grad 
    would then become 100 kilometres. In the end a small instrumental error 
    caused the metre to be off by about 0.2mm and then it took some time 
    before it was realised that the length of the meridian was affected by 
    the geoid and that the impressive but partial measurement performed by 
    Delambre and Mechain would not have resulted in a reliable figure for 
    the whole meridian anyway.
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