NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Children's land-locked "Sextant"
From: Gary LaPook
Date: 2007 Nov 29, 09:59 -0800
From: Gary LaPook
Date: 2007 Nov 29, 09:59 -0800
Gary replies:
Well then, don't spill it.
I've taken sights reflected in puddles of water in snowy road ruts, on absoulutely still sea water in a fjord in Tahaa, and water in a bowl but nothing is as shiny as mercury. Using a level to set up a mirror means you are limited to twice the accuracy of the level and also some possible error if the mirror is not absolutely flat. This means that if you are trying to measure the accuracy of your sextant you will need to find a level that is twice as accurate as the sextant you are testing and probably cost more than the sextant itself. You guys can do what you want to do but I will stick to my little bottle of mercury (and I will be careful not to spill it.)
Alexandre E Eremenko wrote:
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Well then, don't spill it.
I've taken sights reflected in puddles of water in snowy road ruts, on absoulutely still sea water in a fjord in Tahaa, and water in a bowl but nothing is as shiny as mercury. Using a level to set up a mirror means you are limited to twice the accuracy of the level and also some possible error if the mirror is not absolutely flat. This means that if you are trying to measure the accuracy of your sextant you will need to find a level that is twice as accurate as the sextant you are testing and probably cost more than the sextant itself. You guys can do what you want to do but I will stick to my little bottle of mercury (and I will be careful not to spill it.)
Alexandre E Eremenko wrote:
On Thu, 29 Nov 2007 glapook@pacbell.net wrote:There is a big difference in risk from exposure to mercury vapor on an everyday basis for many years in an inclosed space (your example and the classic "Mad Hatter") and the occasional use of it outdoors for navigation. "Why voluntarily expose yourself to" it? because it works very well for this purpose, better than anything else and the risk is minimal.Spilling mercury outdoors will expose fish and other wildlife for many years. Alex.
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