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    Re: Point Venus, May 1774
    From: Alexandre Eremenko
    Date: 2007 Apr 30, 08:12 -0400

    
    Dear George,
    
    > I had completely lost track of
    > where Alex had got to in his study
    > of Cook's observations,
    
    So far I posted two messages on early May 1774
    and one (most recent) on August 27 1773
    all from the first voyage.
    
    > Cook's Journal (Beaglehole vol 2)
    > for early May 74 is no help. Cook is
    > heavily involved in obtaining and
    > preserving his ship's food stocks, and
    > makes no mention of any astronomical observations.
    
    Wales journal does not mention at all
    any observations made by Cook personally.
    Only by Wales and Bayly.
    The observations I was talking about were all made
    by Wales personally. He says so.
    
    > It seems quite likely that those
    > faulty Moon altitudes could have been taken
    > by a middie, using a wooden octant.
    
    See my last message on 1773. In that observation
    it is recorded what instrument was used for the Moon.
    
    > Another possibility might be that the
    > wrong limb of the Moon had been chosen,
    
    Wrong limb would give about 30' error.
    And we have errors of 3'-6' typically.
    Of course this does not affect the Lunars results.
    It seems that they just were negligent.
    (Knowing that precise alt of the Moon is not
    important).
    
    Another curious thing is how they record their
    observations. The Lunars are recorded to whole minutes,
    with frequently added fractions of a minute like
    1/4, 1/3, 1/2, 5/8, 3/4, and once even 1/12.
    I conclude that their vernier did not subdivide
    minutes. (I cannot imagine a vernier which would have
    both 1/12 and 5/8 :-) So they estimated
    fractions of a minute by eye
    (as I do on my SNO). But IC they show with seconds,
    probably the result of averaging.
    
    > I don't have Wales' numbers to work on.
    
    You will have them soon.
    As I said I can mail them so that you don't have to
    wait till July. I can mail only few pages relevant to
    Point Venus, if you wish.
    
    Alex.
    
    
    
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