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    Re: davis a.h.
    From: Joe Shields
    Date: 2001 Apr 24, 11:20 AM

    Having used a shallow dish of water for many years before purchasing a Davis
    artificial horizon, the Davis a.h. is much better.  Not only for the wind
    protection provided by the enclosure, but also the tinted glass cuts down on
    the glare providing a crisper, more comfortable-to-look-at disc.
    I guess the one disadvantage of the pan-of-water type a.h. over a bubble
    type a.h. is its limitation to lower altitude sights.  For instance, I can't
    practice noon shots in my back yard except during Winter months
    (brrrrrr...).
    Of course in the Summer, with our sailing club situated on the North shore
    of our little (~1nm across) man-made lake, short-dip corrected sights are
    the best.
    
    -----Original Message-----
    From  Doug Sterrett [mailto:dwsterrett{at}EARTHLINK.NET]
    Sent: Tuesday, April 24, 2001 12:35 PM
    To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    Subject: Re: Astra IIIB
    
    
    John, please caution people that mercury is highly poisonous and very
    dangerous for laymen to handle.  In many states it is a controlled
    substance.  It is also extremely expensive.
    Humbly submitted by
    Doug
    
    At 12:34 AM 4/25/01 +1000, you wrote:
    >a shallow pan of mercury is perfect 
    >cheers,
    >John
    >
    >At 21:34 23/04/2001 -0700, Yves Arrouye wrote:
    >> > The practice bubble horizon is difficult to use. There is no
    >> > magnification.
    >> > The slit aperture makes me see double of the reference line
    >> > in the sight.
    >> > Combine that with trying to hold the sextant steady so the bubble is
    >> > centered while adjusting the sight ... it can be frustrating.
    >>
    >>I know, I tried it. What's very frustrating is how any small movement
    makes
    >>the bubble go away. But then, I didn't seem to have much success with a
    pan
    >>of water in my garden either. Maybe oil would be better? Anyway, the
    bubble
    >>horizon is on order, and I'll see what my first sights will be. Not good I
    >>imagine...
    >>
    >>YA
    

       
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