The Parallel And The Purchase

From The title of the Phelps and Gorham purchase:

Penn shrewdly obtained from the Duke of York, August 31, 1682, a surrender of all claims to this territory; but one question was left open and was actually disputed for ninety years between the two colonies; the meaning of  'the beginning of the three and fortieth degree of northern latitude.'  Pennsylvania suggested, rather than alleged, that it was the forty-third parallel.  New York argued, that, as the equator is the beginning of the first degree of latitude, so the forty-second parallel is the beginning of the forty-third degree.

The forty-third parallel of latitude crosses the Phelps and Gorham Purchase, passing through it a little north of Geneva, and at the middle of the town of Rush in Monroe county, and, if this line had been the northern boundary of Pennsylvania, all of western New York would have belonged to the former, except an irregular and narrow strip along the shore of Lake Ontario. (See Plate I.)