Letter not found: from George Mason, 9 April 1768. The letter is listed in the Henkels catalog no. 657, item 45, 10 Dec. 1890. According to the catalog, the letter was docketed by GW on 23 Feb. 1789: “The Lines to which this letter has reference were settled by & between Col. Mason and myself the 19 of April, 1769, as will appear (if there should ever be occasion to recur to it) by a Survey thereof made on that day in his presence and with his approbation—Entered among other proceedings of a like sort and tied up in a Book with a green parchment cover, which Book is deposited along with my Land Papers.”

The lines settled by the 19 April 1769 survey were the lines between the part of the old Thompson patent owned by George Mason and a small 300–acre tract, originally a part of the same patent, which GW had bought in 1757 from Sampson Darrell. See Mason to GW, 14 Oct. 1769 and note 2, Darrell to GW, 28 Dec. 1757 and 9 Oct. 1759, and notes, and the map and chart: The Growth of Mount Vernon, 1754–1786, in Diaries description begins Donald Jackson and Dorothy Twohig, eds. The Diaries of George Washington. 6 vols. Charlottesville, Va., 1976–79. description ends , 1:240–41. The survey has not been found, nor has the “Book with a green parchment cover,” but a memorandum of an agreement written in Mason’s hand and signed by GW on 21 April, two days later, settling the boundary lines gives some idea of the problems involved in getting clear title to land, because of variations in surveys, missing deeds, the disappearance of identifying trees, and so forth: “It is agreed this 21st day of April 1769, between the Subscribers that an ancient mark’d Line from Dogues Run to little Hunting Creek formerly run by Thomas Hooper Surveyor of Stafford County as the upper Line of Matthew Thompson’s Sale to Charles Rose for three hundred Acres of Land, now in possession of the Subscriber George Washington, shall for ever be established as the dividing Line between the Subscriber’s Lands in the Neck between Dogues Run & the South Branch of little Hunting Creek, the sd Line beginning upon Dogues Run side at an old stooping white Oak near two or three small sweet Gums, & a red oak now newly mark’d, & a large sweet Gum formerly mark’d, & running across the Neck (by a Line of ancient mark’d Trees as aforesaid) N. 76 d. 30 m. Et 668 poles to two Spanish Oaks & two white Oaks now newly mark’d, standing in the main South Branch of little Hunting Creek; and that the Subscriber George Mason shall make a Deed of Release unto the Subscriber George Washington for the three hundred Acres formerly sold by the sd Matthew Thompson unto the sd Charles Rose to be bounded by the said Line, notwithstanding it contains more than this Quantity; and the sd George Washington agrees to pay unto the sd George Mason twenty shillings Virginia Currency for every Acre of Land more than five hundred & twelve Acres which shall be found to be contained from the Meanders of Dogues Run & the main South Branch of little Hunting Creek between the sd Line, & the upper Line of the Land commonly called Spencer’s patent, as the same was formerly established in a Suit in the General Court between Thomas Marshall plaintif & Sampson Darrell Defendant” (ViMtvL).

On 24 Oct. 1769, as the agreement provided, Mason gave GW a release for what seems to be the same 300–acre tract that had previously been sold to GW by Sampson Darrell. At the same time GW paid Mason £100 for one hundred extra acres of land found to be contained in the tract. The Fairfax County Deed Book for 1769 is missing, but GW’s own copy of the release of 24 Oct. 1769 from Mason was sold in the Birch sale of 1891, catalog no. 667, item 33. See also General Ledger A description begins General Ledger A, 1750–1772. Library of Congress, George Washington Papers, Series 5, Financial Papers. description ends , folio 61, Sampson Darrell to GW, 28 Dec. 1757, 9 Oct. 1759, and notes, and Mason to GW, 14 Oct. 1769, and notes.