TJ’s information was probably obtained from Isaac Briggs during the latter’s visit to Washington and the eastern states with Robert Williams during the spring and early summer of 1804. TJ was at Monticello when they arrived in Washington in mid-April, but could have met with Briggs after his return to the capital on 13 May. Briggs was still in the vicinity in June and July, during which time he traveled to Philadelphia and made purchases for the president. TJ’s financial memoranda record payments to Briggs on 30 June for “mathematical instruments” and on 18 July for a refrigerator made by Briggs’s brother-in-law Thomas Moore. Briggs also apparently visited Monticello sometime after TJ arrived there on 26 July, at which place he took charge of TJ’s letter to Benjamin Hawkins of 4 Aug. (Vol. 43:232, 519-20, 539-40, 671; MB description begins James A. Bear, Jr., and Lucia C. Stanton, eds., Jefferson’s Memorandum Books: Accounts, with Legal Records and Miscellany, 1767-1826, Princeton, 1997, The Papers of Thomas Jefferson, Second Series description ends , 2:1130, 1132, 1133-4; TJ to Thomas Whitney, 9 July).