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Re: Making an artificial horizon
From: Patrick Goold
Date: 2011 Jan 20, 21:57 -0500
From: Patrick Goold
Date: 2011 Jan 20, 21:57 -0500
Well, as long as we are exploring tangents, some might be interested in this, another use of Hg in astronomy.
Patrick
--
Dr. Patrick Goold
Department of Philosophy
Virginia Wesleyan College
Norfolk, VA 23502
757 455 3357
Charles Olson: "Love the World -- and stay inside it."
Patrick
On Thu, Jan 20, 2011 at 7:16 PM, George Huxtable <george@hux.me.uk> wrote:
Jim Wilson wrote-
Yes, but not novel. It had been used for years in lighthouses, to support
| All this talk about mercury reminds me that the one hundred inch Mount
| Wilson telescope is floated in mercury to minimize bearing loads. There's
| not much of it, since a thin layer is all that's required. I thought the
| idea ingenious.
the heavy rotating lens/mirror assembly. The idea was to minimise the
energy needed to drive it, which came from a falling weight, wound back up
to the top of the tower at intervals, by hand. Also, to provide an
effective draught-excluder in gale conditions.
I imagine that in both examples, the flotation relieved the supporting
bearing of most, but not all, of the load, so that the bearing still
provided precise location of the rotating assembly.
Perhaps it was the Mercury, rather than the isolation, which caused the
dementia to which lighthouse-keepers were prone.
George.
contact George Huxtable, at george{at}hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
--
Dr. Patrick Goold
Department of Philosophy
Virginia Wesleyan College
Norfolk, VA 23502
757 455 3357
Charles Olson: "Love the World -- and stay inside it."