NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Mid XIX century Nav
From: Frank Reed CT
Date: 2005 Nov 16, 22:47 EST
From: Frank Reed CT
Date: 2005 Nov 16, 22:47 EST
Alex, you wrote: "Meridian observations (with a meridian circle or teodolite) need a firm base. But what about time sights?" Time sights ashore can be done with an artificial horizon so that yields about ten times better accuracy for a skilled observer than a time sight taken with a sea horizon. Of course, a time sight will tell your you chronometer's error only if you know the longitude of your observing sight. By the date in question, the longitude of Nagasaki was reasonably well known, assuming you trust your tables. If we don't trust the tabulated longitude, you have other options for determining longitude ashore like moon culminations that are generally more accurate than lunars. These depend on a careful determination of true azimuth. -FER 42.0N 87.7W, or 41.4N 72.1W. www.HistoricalAtlas.com/lunars
