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This "impossible lunar"exist in two very similar versions. Maskelyne's 
version, later retracted for a different Moon altitude, was presented 
without additional information. Moore's, not quite the same, was given with 
additional information such as longitude (by account, presumably) of 9º 
West  (not 7º as Antoine mentions), date, and time.

I wonder if Antoine is conflating elements of the two?

George.

contact George Huxtable, at  george@hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
----- Original Message ----- 
From: "Antoine Couette" 
To: 
Sent: Sunday, August 29, 2010 6:00 PM
Subject: [NavList] Re: Impossible lunar example


Thank you Frank for publishing Maskelyne's Comments about our now well 
known "impossible Lunar".

Let us use Maskelyne confession then :

QUOTE

Also Ex. IV p. 31 and 36, is in the same Situation, owing to a Mistake in 
transcribing the Moon's Altitude 71d 6'2" instead of 41d 6'2"

UNQUOTE

So we can now rework our Lunar example with :

20 NOV 1796 TT-UT=14s4

at one same unknown (and still yet to be determined) time - expected to be 
in the vicinity of UT=18h46m - we observe the following three SEXTANT data 
(all assumed to have been observed at the very same instant) :

SUN-MOON SEXTANT DISTANCE 102°57'5, SEXTANT Height of SUNLL=18°47' and 
SEXTANT Height of MOON LL=40°32'

Height of Eye : 20 ft with all other conditions assumed to be standard.

We can compute the following 2 positions :

UT of Sextant Observation #1 = 18h23m49s1 with position #1 at 
N3658.6W14427.7,

and

UT of Sextant Observation #2 = 18h23m35s0 with position #2 at 
S2515.5W17713.4

I did not crosscheck the results published hereabove against Frank's 
Computer results, but they should agree to better that 0.1' as (almost) 
always.

... Well... , both of these positions fall in the middle of nowhere in the 
Pacific Ocean .. . with none of them anywhere near the Greewhich W007° 
meridian ... which we already knew thanks to George's clever insight.

So we might think that Maskelyn's data correction possibly either as 
incomplete - since the UT value is close from the one he has quoted -, or 
as a plausible reason that his initial example was created "ex nihilo" 
since, even corrected with his amended height, this Lunar could NOT have 
happened be anywhere near the Meridien W009° ...

Unless somebody has a reasonable explanation to the above, including any 
and all errors of mine, this "most important question" of ours still 
remains an open one ...


Thank you for your Attention and

Best Regards

Antoine


Antoine M. "Kermit" Couëtte





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