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    Re: Back In Hobby: Some Questions, Please
    From: Alexandre Eremenko
    Date: 2007 Apr 25, 18:17 -0400

    
    Bill,
    
    Indeed, the notion of "full sized sextant"
    apparently evolved:-)
    Nowadays, the largest sextants still in production
    have arc size 162mm (according to Celestaire catalog).
    And they are considered "full-size".
    That is a bit less than 6 and 1/2 inches.
    A great authority of late XIX century (Lecky)
    on p. 70 of his book "Wrinkles of practical navigation",
    says: "Avoid a sextant of less than 8 inches radius".
    And then he mentions
    "...The writer's instrument is a 10-inch Troughton
    divided on platinum".
    
    Let me add few comments of my own.
    I am really interested in this question whether
    the best XIX century sextants (made for the Lunars)
    were better than out modern ones.
    
    I have no way to decide this. I cannot afford a
    "10-inch Troughton divided on platinum"
    in decent condition to test it.
    So I have a modern Russian CNO-T, 6 and 1/2 inch
    and a 1900-or-so C. Plath, 7 and 1/2 inch.
    The modern one is VERY much superior...
    in all respects.
    
    Alex.
    
    On Wed, 25 Apr 2007, Bill wrote:
    
    >
    >
    > Interesting.  Could not quickly locate a reference to "full-sized sextant"
    > in my library so Googled it.
    >
    > I find the following arc radii described as "full sized:"
    >
    > 8"
    > 178mm
    > 7"
    > 6.5"
    > 162"mm
    > 6"
    >
    > Quite a range.  If we consider 162mm to be full sized, the Astra then
    > becomes a 17/18ths (large yacht ;-) size.
    >
    > If we consider Davis's 178mm to be full sized (which approximates the 7"
    > figure I recall), then the Astra is indeed a 7/8ths yacht size.
    >
    > That all reminds me of a pizza bet with my father.  I bet him my 10-year-old
    > 1975 "mid-sized" Chevy Nova automobile was longer than his new full-sized
    > Buick Century.  I won by 2".
    >
    > Bill
    >
    >
    >
    >
    > >
    
    
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