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Alex Eremenko quotes from a Russian translation of Bougainville's Journal.

There is a recent translation into English, edited by John Dunmore, "The
Pacific Journal of Louis-Antoine de Bougainville 1767-1768", published by
the Hakluyt Society, in 2002.

It appears that there are important discrepancies between these two
translations.

An earlier translation into English exists, made by J R Forster (Cook's
naturalist), in 1772, which I haven't seen.

Bougainville's original shipboard journal is kept at the Archives
NMationales, Paris, under Marine 4  JJ 142, No.17.

Alex quotes-

>"On 8:30 November 14 we were on the meridian
>of the Flores island, and at noon within 12 leagues
>to the West in the direction W by S (101 1/4 deg)
>from Montevideo;
>from here I took my departure point as
>Lat. 34d54' S, and Long. 58d57'30" West of Paris...

Alex doesn't state the year here; the only clue being his description as
"the first French circumnavigator (1766-1769)". Although Bougainville left
France in 1766, he had spent a long time on other business in the Falklands
(Malouines) and South America, so his departure from Montevideo didn't
happen until November 1767. This has some interesting implications, as we
will see.

The Hakluyt translation reads as follows (referring to the noon-to-noon
nautical day between noon on Saturday 14th November and Sunday 15th
November, civil dates). My interjections are in square brackets, and
include translations, from a table given by Dunmore, between French
compass-points and British usage. After their departure at 3.30 am (on the
civil day Sunday Nov 15th)-

"At 8 [am] sighted Montevideo bearing W 5deg N, the island of Flores
distant 1 league [3 nautical miles]. Sounded N and S of the island of
Flores 8 fathoms mud and shells.

At 10 sighted Flores bearing W and W 1/4 SW [W by S], its centre distance 4
leagues. 9 1/2 fathoms, same ground.

At midday the most E land bore NE 1/4 E [NE by E], the most W NW 1/4 N [NW
1/4 N], 10 fathoms. From 10 to midday steered E 1/4 NE [E by N] to E 1/4 SE
[E by S]. At midday we were 12 leagues E and E 1/4 SE [E by S] of
Montevideo from which I am taking my point of departure in latitude 34d 58'
South and longitude  58d 18'. I am using Mr Verron's observations. [V?ron
was the astronomer, who seems to have been very competent]. I will add at
this point that this astronomer checked my octant which he found to be very
accurate...."

At the end of that day's log (noon on Sunday November 15th, civil date)
Dunmore quotes Bougainville-
 "at midday estimated run SE 4d 45'E, distance 98'.
Latitude estimated and observed 36d 1'
Longitude estimated 56d 43'   "
[according to Dunmore, Bougainville uses "estimated" to imply dead-reckoning].

=======

You can see from this that the Russian version, as quoted by Alex, was
considerably shortened. It referred to a position "in the direction W by S
(101 1/4 deg) from Montevideo". W by S seems unlikely from Montevideo, and
should presumably have been E by S.

For some reason, there are significant differences between the quoted
latitudes and longitudes of the point of departure, between the Russian and
English translations. I have no idea why; in both cases the longitudes seem
to be taken from Paris. I wonder if Alex can suggest why. It's certainly
the case that the coordinates of the departure point, as quoted by Dunmore,
and the following noon position, accord well (within a couple of miles),
with the length and direction of that 98-mile day's run.

=============

Now we get to the really interesting bit, which so surprised Alex. This
appeared in the journal for the day noon November 21st to noon November
22nd, when Boudeuse was well out to sea.

The Russian translation goes-
>"I also used my stay on the shore [Presumably, at Montevideo] to find the
>correction
>of my octant from the distances between the known stars;
>it turned out that the altitudes measured by this instrument
>were 2" less than the real ones,
>and I always used this correction since then."

and Alex comments-
"NO, I made no misprint: he is talking about 2 SECONDS!"

But the Hakluyt translation gives another version, as follows-

"While on land Mr Verron checked my octant's alidade and the division of
the edge. He made a great many observatons with my instrument on different
days, taking apparent distances of the Eagle and the Lyre Wega [an editor's
footnote here states that these terms were in common use at the time to
describe the constellation Aquila (Arcturus) and Lyra (Vega)] along the
same vertical, and comparing these observations with the astronomical
position of these two stars, he found the height recorded by my octant to
be 2' short."

That 2-minute error seems a lot more sensible than a 2-second error, doesn't it?

==============

Alex adds-

>He also talks a lot about lunar distances. He departed
>2 years earlier than Cook, so the method was quite new then:-)
>Unfortunately I do not have the original book,
>what I am reading now is a Russian translation from
>the French original. That's why I do not cite what he says
>about lunar distances, to avoid double translation.

Dunmore, in his introduction, refers to the French almanac "Connaissance
des Temps", which had been going by then for about 90 years. According to
Cotter, since 1761 this had carried predictions of the celestial position
of the Moon (by Mayer) at 12-hour intervals.

If using that information, the navigator had to interpolate these Moon
positions very precisely (which called for second-order interpolation) and
then compute the lunar distance to the observed Sun or star, at two moments
of time. That's a lot of preliminary work, before what we think of as the
"lunar computation" even starts.

But I wonder whether Bougainville carried with him the first issue (for
1767) of Maskelyne's Nautical Almanac, which used an updated lunar theory
by Mayer. That would have short-circuited much of the labour, because
Maskelyne had arranged to pre-compute much of the difficult stuff.

Bougainville was a noted mathematician, well in with the British
"enlightenment", a member of the Royal Society, and a friend of Banks. He
would have been well in touch with the scientific developments in England
and, surely, the forthcoming almanac.

Maskelyne didn't manage to publish the first almanac, for 1767, until
mid-January 1767, by which date Bougainville had departed, so he missed any
chance to acquire a copy to take with him.

But V?ron, the astronomer, didn't leave France until the Spring of 1767, in
the transport ?toile, to meet up with Bougainville, so he may have been
able to acquire a copy, or copies, of the British 1767 almanac beforehand,
and perhaps to be one of the first to use it in his Atlantic crossing to
South America. All this is simply speculation.

However, the almanac for 1768 wasn't published until 30 December 1767, by
which time Boudeuse and Etoile were well into the Magellan Strait, so from
the start of 1768 they were certainly reliant on the Connaissances des
Temps for the Pacific voyage.

George.

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