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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Help - Unknown Compass Graduation Arrangement
From: Nicol�s de Hilster
Date: 2009 Oct 23, 09:58 +0200
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. Nicol�s --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com -~----------~----~----~----~------~----~------~--~---