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Line with the Transit Instrument. With a Copy of the Sur-
veyors Minutes to the time they left off the 30th of August last
& a Copy of the Minutes of the Commissioners proceedings
at their two last Meetings I shall now send you a neat Draft
or Platt made out by our Surveyors to shew how the Lines
last run cross several of our Rivers, but it was not possible
for them in so small a Draft to shew how the Offsetts
from the two Lines last run interlock or over reach each
others Extremities. You will see by the Instructions given
by the Commissioners to Mess" Mason & Dixon that
those Gentlemen are now employed in taking Observa-
tions at Philadelphia in order to ascertain the true Latitude of
the southernmost part of that City which probably they will
do by the middle of January & I suppose it will be a month
longer before they will ascertain to their satisfaction the true
Latitude of the Point where they are to make their next
Observations. I perceive by the Instructions that in directing
the fifteen miles South to be actually measured from the point
last mentioned the Commissioners have varied from the
Hints, but it seems Messrs Mason & Dixon were of Opinion
that as a Degree was never yet measured in this Latitude it
would be adviseable to measure the said fifteen miles, & when
they have done so the Commissioners are to meet in order to
judge of their Work & to give them Instructions relative to
their running the West Line, which it seems after all that has
been said of the Transit Instrument cannot be thereby truly
or precisely described there being no Movement that Messrs
Mason & Dixon could shew or the Commissioners discover
to bring & keep its Telescope in the plane of a Parallel of
Latitude : It was however delivered by our Commissioners to
the two Gentlemen to be used as they should see occasion,
tho they seemed to think a less complex & more portable
Transit Instrument which they brought with them from Mr
Penn would be of more general use to them in running the
several Lines required. The Transit Instrument not being
contrived as I have already intimated so as to describe a
Parallel of Latitude it will perhaps be a question at our next
meeting whether in running the West Line they shall set off
at Right Angles with the Meridian in which Case they would
always incline to the Southward since the Line described
would be the Arch of a Great Circle, or whether they shall
set off at such an Angle Northward with the true Parallel as
will after running a certain Distance bring them again into
the true Parallel, the Difference is that in the former Case the
Visto will be for the most part if not altogether within this
Province for which Reason we would prefer the other Method,
& in the other Case it will be always except just at the
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Letter Bk. IV
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