NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sextant Accuracy and anomalous dip
From: Bruce Stark
Date: 2003 Mar 22, 15:39 EST
From: Bruce Stark
Date: 2003 Mar 22, 15:39 EST
In response to a posting of mine, Jared wrote: >That sounds logical, but it is not at all the process Combe described. Remember, he's talking about "marching into town to find a flat spot" or finding some local fort and being thrown out of it. He's very definitely NOT at any "local station", and it sounds like he is often some miles away from one, in any random direction. Something is missing from this picture, I think.< I wrote an answer yesterday, but apparently it didn't go through. It went something like this: Jared, Maybe the confusion comes from Capt. Combe's interest in explaining what it was like to use an artificial horizon, rather than what he got from the observations. At a known longitude he could have found the chronometer's error on Greenwich. At an UNknown longitude he could only have gotten a "fresh rate." For either job he could have chosen between time sights and equal altitudes. As to the need for a level spot, perhaps it had to do with convenience in setting up the artificial horizon and sextant stand in proper relation to each other. Also, they had to have a place for the camp stools, and room to crawl around to get in position to take the observation. In some places, because of steep ground and trees, the only flat spot with a view might have been a street. Bruce