GW had long been frustrated in attempts to plot accurately the dividing line between the two halves of the Spencer-Washington grant, because about 1741 the northern boundary of the grant had been moved south nearly 200 rods to accommodate other grants (R. O. Brooke’s survey, c.1741, callahan description begins Charles H. Callahan. Washington: The Man and the Mason. Washington, D.C., 1913. description ends , facing p. 3). Thus, GW did not know whether to run the line as if it were coming from the center of the original northern boundary as stipulated in the 1690 division or from the center of the revised boundary (survey and division by George Brent, 18 Sept. and 23 Dec. 1690, ViMtvL). In addition, many of the marking trees mentioned in the old surveys had disappeared or could not be found (survey by GW, 1–2 Oct. 1759, ViMtvL). Determined to establish at last the exact western boundary of the Mount Vernon tract, GW had invited John West, Jr., and Thomas Hanson Marshall, the two gentlemen who now owned the portions of the old Spencer tract lying on the line, to join him in making the survey begun today. Marshall declined to come, giving first his own illness and then his wife’s as his excuse, probably a legitimate one in the latter case, at least, because Mrs. Marshall died 5 Dec. 1770 (Marshall to GW, 8 and 11 April 1770, DLC:GW; gerald description begins Herbert P. Gerald [annotator]. “Marshall Hall Burying Ground at Marshall Hall, Md.” Maryland Historical Magazine 24 (1929): 172–76. description ends , 173). None of the Spencer tract now remained in that family’s possession, Col. Nicholas Spencer’s grandson William having sold it in various parcels 1738–39. Those besides West and Marshall who now owned parts of the tract were Daniel French, Harrison Manley, the Wade sisters, and GW.