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Cumberland Coast
Survey
EXTRACT of a Letter giving an Account of a Survey
of the N.West Coast of England, in August
1746, at our Expence.
SIR,
I WAS made extremely sensible of the want of correct maps in
the course of my survey; in my opinion, the nation
ought to encourage general meridians thro' Britain at
least from Berwick to the south coast of
England, as has been done in France. Geography
gains ground fast, and by a few observations of the eclipses
of Jupiter's satellites, made at different places by
proper observators, our longitudes might all be corrected.
The principle objection, I own, is the great expence of the
work; but it well known that Moll's little erroneous
trifles, built altogether on copy, took very well, and
certainly in a more curious age, correct ones would not need
encouragement.
It was my business every night to prepare meridians, by the
north-pole, in case of mistakes by the needle, after
allowance made for the position of the pole-star from the
point of the earth's produc'd axis, against my mornings
works. I could not find, that the points of Darwent
mouth bore near so much west as suppos'd in the present
maps, the makers of which, I imagine, depended on the
magnetical meridian more than the solar one.-
And, indeed, as the difference of the magnetical and solar
meridians is very near 18° on this coast, it is not
to be wonder'd that surveys, following the needle, should
throw all promontories so much south of west, as seems to be
the case, in constructing on these principles; the
magnetical being a false meridian, tho' sailors use it for a
true one.
Observations by the magnetical needle uncorrected by the
solar, are at least about 1½ point west of the north.
It has encreased on this coast since 1715 from 14° to
17° 30', where it is now, but is still encreasing.- I
have marked the position of the sands from the best
intelligence - Tho' the sea coast is most useful to be taken
as it appears, for the service of mariners, yet it is great
pity that public encouragement is not offer'd for accurate
maps of the land also.
I began, at the monument on Burgh Marsh, to measure
off the Solway bay; and as the ground was very low, I
took several bases of triangles, to measure the opposite
shore, and fix its
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