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    Re: MA-1 bubble sextant
    From: Richard M Pisko
    Date: 2007 Feb 20, 21:00 -0700

    On Mon, 19 Feb 2007 19:59:01 -0700,  wrote:
    
    > Does anybody have any information about this type of sextant
    > or the similar periscopic ones with a pendulous mirror? Since the
    > bubble ones are much more common is the reason for this that the
    > bubble ones work better or are they less expensive to manufacture?
    >
    One comment, not on sextant artificial horizons, but on similar solutions
    for theodolites and levels.  I have a Wild T1-A that uses the reflecting
    under-surface of liquid in a capsule to provide the zero for vertical
    angles automatically, instead of having to watch the ends of a leveling
    vial.  (That is the meaning of the "A" in the model description.)  I also
    have a Kern DKM2-A that uses a pendulous prism/mirror for the same purpose.
    
    Giving a little tap to the tripod with cause a noticeable quiver in the
    vertical angle reading in the hanging mirror type (and lets the operator
    know it's working), but is almost nonexistent in the bubble type . . . so
    the dampening is much quicker for the bubble.  Also, while both
    instruments should be treated gently, there seems to be much more of a
    point made of the delicate nature of the suspension wires of the pendulous
    prism.
    
    I would be interested in reading how well the two types of sextants behave
    for you.
    
    --
    Richard . . .
    Using Opera's e-mail client since Dialog, "the Dog", died.
    
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