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On 16 Dec 2004 at 9:50, Alexandre Eremenko wrote:

> Anyway, it is interesting to know where the advise
> "not to measure altitudes" comes from and what was
> the justification.

This is an interesting question and one that has been discussed here
before (though I don't recall if anyone was able to answer it
satisfactorily). Thompson was instructed in celestial navigation by Philip
Turnor who was one of Maskelyne's computers for the nautical almanac. It
is hard to believe that Turnor wasn't aware of the standards of practice
advocated by the cognescenti.

I just briefly flipped through one of Peter Fidler's notebooks and out of
25 lunars, there wasn't a single instance of an altitude exceeding 55?. So
the idea that an artificial horizon would limit the number of altitudes
that could be taken seems to be without merit (at least for this
latitude). Did the inherent error of the moon's position, and the
resulting uncertainty of any lunar, lead people to decide that measuring
altitudes just wasn't worthwhile?

Ken Muldrew.

   

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