So early, however, as about the close of the year 1763, four or five years before the running and marking of Mason and Dixon’s line, Mr. Rittenhouse was employed by the Penn family in making some geographical arrangements, preparatory to the final establishment of those boundaries. He was engaged to perform this service, by the Rev. Mr. Richard Peters, (afterwards D. D. and rector of the united churches of Christ-Church and St. Peters, in Philadelphia,) who then officiated as the Governor’s provincial secretary; a gentleman of learning and great worth; and one who, on various occasions, manifested a friendship for Mr. Rittenhouse, as well the high opinion he entertained of his abilities. The particular department of that business thus committed to Mr. Rittenhouse, seems to have been the fixing of _the Circle_,—or at least, the tracing of its course or route, topographically; and this was, certainly, a matter of no little difficulty. That this service was performed to the satisfaction of the then administrators of the government of Pennsylvania, and that it was an arduous one, will appear by the following extract of a letter from Mr. Rittenhouse to the Rev. Mr. Barton, dated the sixteenth of February, 1764.[101] ----- Footnote 101: This letter contains, likewise, a short narrative of an occurrence which excited much feeling, and claimed a considerable portion of the public attention, at the time. As Mr. Rittenhouse’s account of the transaction referred to, will serve to shew that he was not an indifferent spectator of the political events of that early day; and, further, that he was zealously disposed to support the legitimate authority of the government, in order to suppress illegal and disorderly proceedings, subversive of the laws and dangerous to the public peace and safety; this part of his letter to Mr. Barton (of the 16th of February, 1764,) is also presented to the reader.