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    Re: Slocum's lunars
    From: Fred Hebard
    Date: 2003 Dec 23, 11:24 -0500

    I agree with the conclusion, given the premise.  The premise has not
    been established with certainty however.
    
    Fred
    
    On Dec 23, 2003, at 10:47 AM, Steven Wepster wrote:
    
    > Hi all,
    >
    > Concerning the errors that Slocum would have discovered, let me add
    > this.
    >
    > An article appeared in the 'Navigation'  journal (Vol. 44 no. 1, 1997)
    > in which the author (S.Y. van der Werff) discusses lunar distances and
    > particularly the lunar distance observation of Joshua Slocum on june
    > 16, 1896, shortly before his landfall on Nukahiva. He comes up with a
    > completely different kind of error that Slocum discovered and
    > corrected.
    >
    > Van der Werff notes that the Nautical Alamanc uses the astronomical
    > date convention, i.e., a new day begins at noon, not at midnight. The
    > layout of the lunar distance tables is such that one can not be
    > mistaken by 12 hours, but not so the right ascension and declination
    > tables. Van der Werff's suggestion is that Slocum accidentally took
    > the RA/Dec values for a time 12 hours off (12 h too late, actually).
    > Slocum's 'discovery', then, was that the tables were 12 hours off.
    >
    > If that was indeed the error that Slocum made, I conclude that he was
    > _very_ unfamiliar with the time convention in the almanac. He would
    > have had no earlier occasion to stumble over this difference of 12
    > hours, or at least no such occasion had occured in the voyage with
    > 'Spray' and for quite some time before. It would imply that usually he
    > took from the almanac only data that were forgiving of such an error:
    > declinations, but no right ascensions. I would conclude that, on the
    > large, Slocum's only means of astronomical navigation was by meridian
    > altitudes.
    >
    > Does this appear as a likely scenario to list members?
    >
    
    
    

       
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