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    Re: Newtons octant
    From: Michael Daly
    Date: 2007 Nov 15, 16:28 -0500

    George Huxtable wrote:
    > There is some serious misunderstanding going on.
    >
    > Mike Daly questioned Ted Gerrard's account
    
    First misunderstanding - I only commented on Nicolas' speculation on why
      Newton's instrument wasn't manufactured or used in significant
    numbers.  I have not made any relevant comment on Ted's posts.
    
    > So what did the artist of that drawing
    > have to go on? As far as we know, only Newton's text, and no "attached
    > scheme". No doubt, he interpreted that text as best he could, with the help
    > of the experts of the day, but that doesn't make that drawing an authentic
    > representation of what Newton's scheme would have been. And then, in another
    > indirect process, that so-familiar engraving was made, presumably from that
    > drawing. There are discrepancies to be found between those three documents,
    > the letter, the drawing, and the engraving, which Ted Gerrard goes into,
    > though I don't go along with Ted about the importance of every such detail.
    
    Second misunderstanding.  The drawing is irrelevant.  I know what the
    text says and it states the instrument is a brass plate with a
    three-four foot scope attached.  What is the problem here?
    
    > | So - why would someone willingly look forward to holding and taking
    > | measurements using a triangle of brass with a 3-4 foot telescope on it?
    >
    > I'm not sure what point Mike is trying to make here. You have to make the
    > best of what the technology of the day allows.
    
    Compared to a long telescope for a lunar method with no reliable tables
    for general use? - I'd say the technological choice is a Davis Quadrant
    and a ship's log.  For something as simple as meridian altitude, the
    Davis quadrant wins hands down in the eyes of a mariner in 1700.  This
    discussion is about a crude instrument that appears roughly 70 years
    before lunars are ready for prime time.
    
    Mike
    
    
    
    
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