A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Gary LaPook
Date: 2020 Jul 24, 23:12 -0700
http://fer3.com/arc/m2.aspx/Mercury-artificial-horizons-LaPook-dec-2013-g26056The sheilding does work with a bowl of any liquid.
I have only 7.4 ounces of mercury which, indeed, I have had since Hector was a pup. Actually since about 1975, just 45 years. It is probably the bare minimum that can be used since it only makes a puddle only 3 inches in diameter. Since the miniscus distorts the edges of the puddle I put a stop on top of the bowl with a 2 inch diameter through which to sight the mercury. This provides for a very small field of view and you have to be in a very stable position to hold the sextant steady enough to keep a star in view. I would like to have more. I found a site that sells 100 grams (3.5 oz) for $20 so, from that site you would need, as a minimum, 200 grams for $40. There is another site that sells 100 kg for $550.00 which appears to sell smaller quanities. It would be wonderful to be able to order 1 kg, I think I will look into it tomorrow. I keep mine in a glass bottle with sealed lid. When you use meercury it develops a dross on top so you simply poor it into a t-shirt and with a gloved hand, squeeze it through the cloth and it comes through shining in little balls into the tray, the dross is caught in the fabric. Make a little funnel out of cardboard for pouring the mercury back in its jar after taking your sights. Then dispose of the t-shirt, rubber glove and funnel inside two plastic bags. Mommentary contact with the mercury will not harm you but it is best to do all of this outside. Be very careful not to spill any since it is almost impossible to pick back up, it's not called "quicksilver" for nothing.
And it is legal: