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Chuck Griffiths wrote:

> [snip] I finally got around to trying the artificial horizon approach that
> you had suggested, George, quite awhile ago. [snip]
> I've had good success with Moon, Sun,
> Venus, and Jupiter altitudes. I've not, however, had much luck finding stars
> in my artificial horizon. I've tried both used engine oil and molassas, I
> prefer the molassas. In either case, though, I find stars don't offer a very
> bright reflection. Anyone have any suggestions?

I purchased a Davis artificial horizon a while back and have tried using it
with only limited success -- Sun easy, Moon in daylight marginal. To date, I
have been using cooking oil (easier clean-up than engine oil and non-toxic).

It occurred to me that the best liquid would be mercury. It would be
entirely opaque, so that the only reflection would be from the surface. It
would have near 100% reflection of light. And its density would mean that
there would be essentially zero disturbance of the surface by wind etc.

Does anyone know whether it is possible for individuals (as distinct from
chemical laboratories) to buy liquid mercury these days? I know that it was
available years ago (we used to play with it as kids) but I rather suspect
that modern concerns about toxicity will have led to all kinds of
restrictions -- even though mercury in its elemental form has quite low
toxicity provided that it is not heated.


Trevor Kenchington

   

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