John Lukens, and Thomas Hutchins. They accepted the appointment in a letter in which they say, “An anxious desire to gratify the astronomical world in the performance of a problem which has never yet been attempted m any country by a precision and accuracy that would do no dishonor to our characters, while it prevents the State of Pennsylvania from the chance of losing many hundred thousands of acres secured to it by our agreement at Baltimore, has induced us to suffer our names to be mentioned in the accomplishment of the work.”
The commissioners on behalf of Virginia were James Madison, Robert Andrews, John Page, and Andrew Ellicott. In April, Rittenhouse was busily engaged in constructing the necessary instruments, and in June he, with Lukens, Page, and Andrews, erected an observatory at Wilmington, Delaware, where they made a series of sixty observations of the eclipses of the moons of Jupiter before their departure. Page and Lukens were unable to endure the fatigue and labor of a six months' journey through the wilderness, and returned home, but the others accomplished their task with entire accuracy and certainty, and having ascertained the lines and the southwestern corner of Pennsylvania, marked them with stones and by killing trees. The following summer the western boundary of that State was fixed by Rittenhouse and Andrew Porter on behalf of Pennsylvania, and Joseph Neville and Andrew Ellicott on behalf of Virginia. For that portion of the line north of the Ohio River, Ellicott also acted for Pennsylvania. It was the most important work of the kind in which Rittenhouse was ever engaged, and to the general confidence in his skill was largely due the settlement of this serious and alarming controversy. In 1786 he and Andrew Ellicott on behalf of Pennsylvania, and James Clinton and Simeon Dewitt on behalf of New York, were
