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    Re: mirror horizon
    From: Fred Hebard
    Date: 2011 Mar 23, 16:53 -0400

    Patrick,
    
    Three leveling screws would be easier to operate.  In fact, one often
    only needs to operate two of the three to level a device.  Of course
    a bubble level is easier to use than a uni-directional level.
    Perhaps course level with a bubble level and then fine with the
    machinist's.
    
    Fred Hebard
    at the other end of your state, about the same latitude.
    
    
    On Mar 23, 2011, at 4:16 PM, Patrick Goold wrote:
    
    > I have finally put together an artificial horizon using a front-
    > surface mirror.  My hope is to be able to do star and planets
    > sights with it, which I cannot do with my Davis artificial
    > horizon.  I found an inexpensive optical quality mirror on-line.  I
    > drilled and tapped four holes in a cheap polypro cutting board for
    > inch-and-a-quarter-long 3/8th-inch machine-thread bolts to serve as
    > levelers and then attached the mirror using standard bathroom
    > mirror brackets.  The trick will be getting the thing adequately
    > level.   William Morris kindly supplied me with a very sensitive
    > level vial.  It is not mounted to the device.  I set it diagonally
    > across the mirror and level it, move it to the other diagonal and
    > repeat, switch it end to end and repeat both those steps and then
    > repeat as necessary.   A picture of this simple apparatus is
    > attached.  Any suggestions about how to improve it (without vastly
    > increasing its cost) would be welcome.
    >
    > I haven't yet taken any sights using it.  It takes twenty minutes
    > to level the thing, sitting at my dining room table.  That is,
    > provided no one is moving about on the ground floor of my house
    > while I am doing it.   The level is very sensitive.  It will not be
    > easy getting it set up outside.
    >
    >
    >
    > --
    > Dr. Patrick Goold
    > Department of Philosophy
    > Virginia Wesleyan College
    > Norfolk, VA 23502
    > 757 455 3357
    >
    > Charles Olson: "Love the World -- and stay inside it."
    >
    > 
    
    
    
    
    

       
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