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: Fred Hebard
Date: 2007 Nov 29, 08:25 -0500
From: Fred Hebard
Date: 2007 Nov 29, 08:25 -0500
I'm not sure the risk is minimal. Other solutions work fairly well, such as using a machinist's level on a flat mirror or cooking oil over Karo corn syrup. On Nov 29, 2007, at 8:17 AM, glapook@pacbell.net wrote: > > Gary writes: > > > Navigators have used mercury for years (Lewis and Clark used it when > crossing America) and I have never heard of any ill health effects > when used in this manner. 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. > > gl > > On Nov 28, 5:06 pm, "Robert Eno"wrote: >> Quite a few years ago -- I think it was during a course where we were >> learning how to lab pack hazardous waste -- we were told a story >> about the >> high incidence of minimata disease amongst high school science >> teachers. The >> cause? Broken mercury thermometers and the students' practice of >> simply >> dumping the waste mercury down the sink drain. Mercury being a >> very heavy >> metal, simply lodged in the sink trap and stayed there for years, >> slowly >> volatilizing and dispersing in the science lab. The science teachers, >> because they spent so much time in the lab, day after day, year >> after year, >> suffered a much higher than normal body loading of mercury. Result, >> short-circuited nervous system. >> >> Unfortunately I do not have a citation for this story but can >> probably find >> one from a colleague. >> >> Not to dismiss what Geoffrey has written, but in my opinion -- and I >> regularly deal with hazardous wastes -- mercury is not something >> to be >> trifled with, nor would I ever recommend it to anyone for use as an >> artificial horizon. I may come off sounding like a scared old >> maid, but the >> world being what it is nowadays; that is loaded with contaminants >> of all >> kinds, why voluntarily expose yourself to even more? >> >> Robert >> >> ----- Original Message ----- >> From: "Geoffrey Kolbe" >> To: >> Sent: Wednesday, November 28, 2007 4:08 PM >> Subject: [NavList 4154] Re: Children's land-locked "Sextant" >> >>> Gary LaPook wrote:- >> >>>> With use it develops a dross floating on the surface which can be >>>> removed by filtering it through a piece of cloth like an old t- >>>> shirt. >>>> You have to twist the cloth to force the mercury though the >>>> cloth and >>>> it comes though in shiny little balls leaving the dross in the >>>> cloth >>>> which I then dispose of. You should probibly wear gloves when >>>> handling >>>> the mercury like this. >> >>> In the 1960's the old Royal College of Science in London was >>> pulled down >>> to >>> build Imperial College, the British attempt to emulate MIT in the >>> United >>> States. >> >>> The Spectroscopy labs in the RCS had long been plagued with the >>> problem >>> that continuum spectra always had absorption lines of mercury on >>> them. On >>> taking up the parquet floor in the lab, a veritable lake of >>> mercury was >>> found underneath! As far as I know, all the researchers of that >>> era lived >>> to a ripe old age, despite working for many years in an >>> environment where >>> the mercury vapour in the air was probably at saturation point. >> >>> Not that I am advocating that we should not take suitable >>> precautions when >>> using poisonous substances like mercury - its just that people >>> somehow >>> seem >>> to be more susceptible to such things than they used to be in times >>> past.... or, at least, that is the perception. >> >>> Geoffrey Kolbe > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---