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    Re: Troughton's reflecting circle
    From: Brad Morris
    Date: 2009 May 21, 17:01 -0400

    Hi Bill
    
    I thought the definition of a "tormented sextant" was one in which the navigator so over-used the
    adjusting screws on the mirror that they were loose in the tapped hole.  The screws had
    been turned so many times that the hole is worn out or deformed.
    
    I have encountered screws like this in my career, just not associated with 
    sextants.  This occurs with adjustment
    screws and soft materials.  When the screw deforms the material, it takes a 
    memory or a set.  When the screw need
    be marginally adjusted in this region, the screw finds that same set, precluding adjustment.
    
    Needless to say, I went over my sextant, using the methods and practices indicated by Bowditch.  It was
    out of alignment as received, probably due to Lecky and Troughton's messages.  
    I adjusted it into alignment.
    Having done many optical adjustments on many pieces of other equipment served 
    me well.  No need to do it again,
    as it is treated like a precious instrument, not a common tool thrown into a drawer.
    
    Message: don't over-tighten the mirror adjustment screws.  Perform your 
    adjustments and be happy.  There is no
    need for absolute perfection.
    
    Best Regards
    Brad
    
    
    
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