NavList:

   

Reply

Gary LaPook wrote-

"You state that the Scillies were plotted ten nm north of their true
positions. I am looking at Edward Wright's chart published in 1599,
more than one hundred years before the disaster."

That chart can be found in David W Waters' "The art of navigation in England 
in Elizabethan and early Stuart times" (1958), which I recommend. The chart 
is at plate LVIII. And a remarkable piece of work it is.

"Bowditch (1962 ed.)
gives the modern position of Bishop Rock as 49� 52' north and 6� 27'
west and of the Lizard as 49� 58' north and 5� 12' west each of which
are confirmed by Google Earth. Wright's chart gives the latitude of
the Scillies as 49� 55' north only 3 nm north of the true position.
The latitude of the Lizard on Wright's chart is 50� 00' north, two nm
from its correct position."

I agree with those latitude assessments, that Gary has made from the chart. 
They are, as he says, very near to the true positions.

 What chart was Shovel using that had less
accurate latitudes than Wright's chart?

Probably that by Greenville Collins, who had been appointed by King Charles 
II in 1682 to survey the coasts of Great Britain, there being at that time 
"no sea-charts and maps of these Kingdoms but what were Dutch, and those 
very erroneous". The charts were made over the next 7 years, and published 
in 1693 as "Great Britain's Coasting Pilot". Those charts continued with 
little change until the last publication in 1753. And they had serious 
errors, particularly around Scilly and Lizard, which could, and should, have 
been put right; but weren't

Between Wright, in 1599, and Collins, in 1682, there had been little 
improvent in seagoing instrumentation. The cross-staff was still in use, and 
the backstaff had become adopted for observing Sun altitudes, but its main 
advantage was in its eyesight-saving feature rather than in greatly 
increased accuracy.

Also interesting is that Wright has a scale of longitudes using Cape
Verde as the prime meridian.

Yes, that's a remarkable feature of the Wright chart, at such an early date. 
It was an outstanding piece of work. It was also the first printed chart to 
use the Mercator projection. There were earlier charts using that 
projection, but they were manuscript.

Using Wright's chart he gives the
longitude of Bishop Rock as 8� 20' east while modern longitude gives
it as 11� 04' east of Cape Verde. (Cape Verde is 17� 31' west of
Greenwich.) Wright puts Bishop Rock 121 nm west of its correct
position which isn't too bad using Cape Verde. Wright put the Lizard
at 10� 05' east of Cape Verde so 1� 45' east of Bishop Rock. The
modern difference is only 1� 15' making a 30' difference, an error of
19 nm.  (I will scan this chart in tomorrow)

Thanks to Gary for introducing that topic.

George.

contact George Huxtable at george@huxtable.u-net.com
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.



--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---

   

Reply