Following his September visit to Bedford County and surrounding areas with José Corrêa da Serra and Francis W. Gilmer, Jefferson returned in November 1815 to expand on his earlier scientific observations and make more extensive geometrical calculations of the altitude of the Peaks of Otter. For this purpose he brought surveying tools from Monticello, including a theodolite made by the British instrument-maker Jesse Ramsden (a photograph of which is reproduced elsewhere in this volume). Jefferson stayed with his friend Christopher Clark at Mount Prospect, the latter’s plantation, from about 8 to 12 Nov. 1815. Jefferson wrote that he devoted five days to making observations followed by five days of calculations based on this data. He probably began the Labeled Diagrams printed below before making his field observations in order to plan the calculations he would make. A summary of Jefferson’s findings, which revealed that the Peaks were not as high as had been anticipated, soon found its way into the Lynchburg Press. The version reprinted in the Richmond Enquirer is given below (MB description begins James A. Bear Jr. and Lucia C. Stanton, eds., Jefferson’s Memorandum Books: Accounts, with Legal Records and Miscellany, 1767–1826, 1997, The Papers of Thomas Jefferson, Second Series description ends , 2:1313, 1316; TJ to Clark, 2, 5 Nov. 1815; Clark to TJ, 2, 5 Nov. 1815; TJ to Charles Clay, 18 Nov. 1815).