NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Arificial Horizons and Tea
From: Bruce Stark
Date: 2003 Jul 10, 20:22 EDT
From: Bruce Stark
Date: 2003 Jul 10, 20:22 EDT
George, It's just a guess, but I imagine the English instrument makers of that day could turn out a bubble level as accurate as you could wish. No doubt it would be expensive. I believe Lewis used the water horizon unless the object was too dim to reflect in it. Though mercury horizons were standard, the captains didn't take one, probably for the reasons Kieran has laid out. The captains certainly had no concern about health issues with mercury. Must have had enough in their medical kit to fill several artificial horizon flasks. They used it to treat syphilis and, in Dr. Rush's pills -- which the men spoke of as "thunder bolts" -- as a laxative. I don't have the Journals for the Fort Mandan part of the trip, but understand Lewis chose the liquid horizon for his observations there. This when the river and everything else was frozen solid. "Artificial horizon drinkability" could have been a factor, since the only thing that would stay liquid in the pan was whisky. Others will have to answer your questions about leveled horizons. But I think one problem with them is that it's not always easy to find, or set up, a base that can be depended on not to shift slightly. Bruce