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    Re: Artificial horizons
    From: Fred Hebard
    Date: 2003 Jul 11, 08:53 -0400

    I thought about this a fair amount, and came to the conclusion you'd
    have to put adjustable feet on corks or somesuch to float the mirror.
    It would then be a real pain to level the corks, although that could be
    done.  And you'd have to lock the screws.  Additionally, the buoyancy
    of corks might change.  Worst of all you would need to assess the level
    optically rather than putting a level on the glass, which might tilt it.
    I also thought about reducing the specific gravity of the mirror
    substance rather than increasing the specific gravity of the fluid, but
    don't know enough about materials to assess the stability of such
    substances.  Any damage whatsoever to your floatable mirror would
    require recalibration.
    A completely different option would be to level a beam of light and
    sight on that as you would a natural horizon.  But visualizing the beam
    might require smoke or fog.
    I think the two basic designs of a liquid surface or a black mirror may
    be the best.
    On Thursday, Jul 10, 2003, at 23:34 US/Eastern, Bill Arden wrote:
    > This thread has gotten me to thinking ...
    > The best thing about a liquid artificial horizon is that it is
    > gravitationally driven to be flat and level, but it suffers from
    > breezes.
    > The best thing about a mirror artificial horizon is that it's
    > permanently flat, but it's hard to make it level.
    > Has anybody tried floating a mirror on a liquid bath? You could glue
    > it to a piece of styrofoam, and if it were only slightly smaller than
    > the pan it's floating in, there wouldn't be much room for wind to
    > disturb the liquid.
    > I haven't tried it (this is just a gedanken experiment) - has anybody
    > else?
    > Regards,
    > Bill Arden

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