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Correspondence of Governor Sharpe. 469
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Instruments for taking Observations at the Center of New-
castle & the Middle Point of the Line that was run in 1751
from Fenwix's Island I cannot tell, but if the Surveyors can
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Letter Bk. IV
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run the Meridian or North Line which they have been now
employed on with such Accuracy & Truth as they seem to
think they can, I apprehend that the exact Difference of
Longitude between the Center of Newcastle & the abovemen-
tioned Middle Point will be more truly discovered by the Sur-
veyors running the North Line they have already begun &
another straight Line from the Center of Newcastle to inter-
sect it, than by any Astronomical Observations, & tho we
should not by running these Lines be able to determine to so
great a degree of Accuracy as might be wished what is the
true & exact Difference of Latitude between the Center of
Newcastle & the said Middle Point (by reason of the great
difficulty of measuring a Line of such Extent horizontally) yet
an Error that may arise from the Mensuration might possibly
be discovered by taking Observations carefully at the two
Points for I am told that the Latitude of two Points on the
Surface of the Earth might by a skillful Observer & with a
proper & good Instrument be determined to a Second, which
is equal to 102 feet measured on the Surface of the Earth.
As I am apprehensive from what passed between the Commis-
sioners who were appointed by Your Ldp's Father & the Pro-
prietors of Pennsylvania to carry the Articles of 1732 into
Execution that the Commissioners now appointed to finish the
Business may at times differ in Opinion about the best Mode
of executing this or that particular part of the Work, I should
be very glad if Your Ldp would submit some queries which I
shall take the Liberty to transmit & such others as Your Ldp
may think fit to the Consideration of some Gentn who have
devoted a great part of their Lives to the Study of the Math-
ematicks & whose Reputation is established, such I presume
are Doctor Bradley Regius Professor of Astronomy at Green-
witch, Mr Senex the Map-Maker & Mr Cockayne who reads
Lectures at Gresham College, but as these Gentn may not be
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p. 148
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apprized of all the Difficulties which will attend running Lines
on the Surface of the Earth some thro a Forrest, some over
Boggs & Marshes & others over a hilly or mountainous
Country & the Difficulties which will attend the measuring such
Lines horizontally your Ldp will not perhaps think it amiss to
submit the Opinions or Schemes of these Gentlemen or any
other Theorists whom you may be pleased to consult to the
Consideration of some Person that hath been used to run
& measure Lines on the Surface of the Earth, for oftentimes a
Thing might appear very easy in Theory which the best Artist
cannot carry into Practice. Among the Queries which I have
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p. 149
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