Commissioners had been appointed by both governments and they did nothing but wrangle for the eighteen months allowed in the agreement, and Baltimore believed this made it of no effect.
The Penn family won in court and the conduct of Baltimore was censured.
Frederick, the sixth Lord Baltimore, declined to be bound by any act of his predecessors, and again many years were wasted.
In 1760 a new agreement was made which was practically identical with the one of 1732. Commissioners on the part of Pennsylvania were the Governor, James Hamilton, Richard Peters, Reverend Dr. Ewing, William Allen, William Coleman, Thomas Willing, Benjamin Clew, and Edward Shippen, Jr., a selection which assured good and faithful performance.
The first three years were spent by the surveyors employed in marking the lines of Delaware. The circle around New Castle was drawn by David Rittenhouse, and added much to his reputation.
This work proceeded too slowly and on August 4, 1763, Thomas and Richard Penn, and Frederick, Lord Baltimore, then being together in London, agreed with Charles Mason and Jeremiah Dixon, two well known English astronomers, “to mark, run out, settle, fix, and determine all such parts of the circle, marks, lines, and boundaries, as were mentioned in the several articles or commissions, and were not yet completed.”
Mason and Dixon arrived in Philadelphia, November 15, 1763, and forthwith engaged in work.
They began their survey by ascertaining the latitude[latitude] of the southernmost part of the City of Philadelphia, which they agreed was the north wall of the house then occupied by Thomas Plumstead and Joseph Huddle, on the south side of Cedar Street. They determined it was 39° 56' 37.4”. This was ascertained December 30, 1763, and the actual survey of the boundary line properly began on this date.
During January and February, 1764, they measured thirty-one miles westward of the city to the forks of the Brandywine, where they planted a quartzose stone, six miles west of the meridian of the court house in West Chester.
With this stone as a fixed point they determined the point from which they should start to run the horizontal line of five degrees longitude to fix the southern boundary. This was of course the northeast corner of the State of Maryland.