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Ted Gerrard wrote:
> *
>
> Regarding my note 3740 relating to the Shovell disaster Nicolas wrote
>
> _Where did that number of "7 backstaff noon sights" originate from? It is
>
> not based on the article in the UK Times, neither did it come from May's
>
> work 'The Last Voyage of Sir Clowdisley Shovel'._
>
> To be honest I'm not sure of the question Nicholas poses. Is he asking 
> whether the _7 observed latitudes_ reported by May (fig 3, p 330 - The 
> Last Voyage of Sir Cloudisley Shovell) and illustrated on page 149 of 
> my own recent book, and which were extracted from surviving log books, 
> were really noon sights taken with a back-staff (Davis Quadrant)?
>
> Or is he asking if the sights may have been taken at some other time, 
> or by some other sort of instrument or even not taken at all, but 
> merely written into the 7 log books as _observations_ when they were 
> merely DR estimates? Which might indeed be the case and would explain 
> why all 7 were biased entirely to the south of the fleets true position.
>
> *
What I indeed want to know is if they were taken with back-staffs (or 
more specific Davis Quadrants) or with other instruments.
> *
>
> Unfortunately for nigh on 2000 poor souls, none of the fleet 
> navigators had access to a Newtonian twin-mirrored octant, an 
> instrument Shovell and the Admiralty were familiar with.
>
> *
That was indeed unfortunate, but then, Newton's instrument never came 
into production. 'Why not?' remains another question.

Nicol�s


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