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Frank, from one your answer to Fred, one can assume:

- the scarcity of Slocum's remarks about noon observations is the proof that 
such observations were so common for him that he didn't pay attention to them 
in his narration

- the scarcity of Slocum's remarks about lunars is the proof that he didn't 
use lunars in other times than he mentioned it explicitly

Am I right in following your argumentation?


But to be more positive, I want to stress the detail of Slocum's text that 
wasn't mentioned up to now in the discussion, if I am not wrong: Slocum says 
explicitly that after ascertaining the great error of his lunar observation 
near Nukahiva "In about an hour's time I took another set of observations 
with the utmost care; the mean result of these was about the same as that of 
the first set." Only in the following sentence, he tells us the story about 
the wrong table value corrected.

Therefore, he should use the same column value for both sets of lunars, 
distant for an hour. Which value could stay constant for an hour in lunar 
tables? I checked three Bowditch's methods from older editions (up to 1851; 
one of them is Thomson's method), Elford, Norie, Dunthorne and Borda and I 
cannot imagine now, which term in their expressions can be constant for an 
hour, if we exclude the theoretical possibility that one body was measured on 
both sides of meridian in the same altitudes. (I cannot check Chauvenet's 
method, as I have no details about it.)

Moon's H.P. can remain the same for this interval and in original Thomson's 
tables (not in Bowditch), there is the table with proportional logarithms of 
H.P.  to facilitate the calculation. Another possibility is that the 
proportional logarithm for the pertinent three-hours-interval of tabulated 
LD's was wrong in the Nautical Almanac of this year. Or ...?


Jan Kalivoda

   

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