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At a certain moment in time George wrote [NavList 1745]:

>Well, it isn't so simple to make a map of an unknown coastline as you 
>"meander" along it. Land surveyors can measure a baseline and take 
>bearings from its ends and triangulate from that. From sea, any 
>baseline is somewhat fluid. For a coast that tends North-South, it can 
>be done by creating a baseline between two sea-positions with spacing 
>determined by precise celestial latitude measurement. Where it tends 
>East-West, it's much harder, when the surveyor lacks a chronometer, as 
>Cook did on that first circumnavigation, and had only lunars, and dead 
>reckoning, to rely on for longitude differences.
>
>  
>
I discussed this bit the second evening in Bar du Mus�e with Jeremy. As 
you all know I am a hydrographic surveyor [NavList 1734] and with my 
background I do see an option of using a plane table on board of a 
vessel. As the plane table needs a fixed orientation this could be 
obtained by using a far direction (mountain, cliff). Any movement of the 
ship would be small in comparison to this far direction. If they added 
two visors to the plane table and operated it with two men (one for 
orienting the plane table using the visors on this far direction and one 
for drawing the lines using an alidade) it would have been possible to 
do a plane table survey.  The survey itself would only take a minute or 
so as the main goal of the plane table would be getting the reference 
lines on paper. Filling in the details could be done on sight.

The 'double protractor' with compass Jeremy showed may have been very 
usefull as well as they might have been able to do some resection with 
that. I say 'might' as I would have to test the possiblilities of this 
instrument. The resection could be done using specific landmarks, that 
were well visible during the voyage.

It is known that longitude posed a problem as Cook cut some of his field 
sketches in two (in north-south direction) to correct for longitude errors.

As someone after Jeremy's paper suggested it would be a good idea to 
check the lunar distance tables Cook used for errors, in order to find 
out the influence of them (if there are any) on the survey.

Nicol�s


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