Daily Record, 1 July 1776-18 December 1799

Library of Congress: Thomas Jefferson Papers, Series 7: Miscellaneous Bound Volumes, Volume 2: Weather Record, 1776-1818.

25 pp., sewn together with 23 pp. of miscellaneous notes.

At head of first page: “[17]76. Farenheit’s thermometer”; heading on time columns, July 1776: “H. Min.”; February–March 1778 (inconsistent): “H. M.”; column headings, 5–12 June 1778: “hour | Thermometer,” and 13–18 June, “hour | Thermom | Barom.”; 19 June 1778, “day | hour of observation of Thermom. & Barom. | Therm. | Barom. | hour of observation of next 3 columns | Wind. from what point. | force of do. | Weather. | leaves, flowers, wild fruits first appear<ing> or disappear<ing> | Birds, insects &c first appear or disappear. | Miscellanea.”; following the entry for 9 July 1778 at the foot of a page, the next page begins with 16 April 1779 (see 10 July–9 September 1778 record, Historical Society of Pennsylvania, and 4 January–15 April 1779 record, New-York Historical Society); following the record for 1 May 1779, observations continue on the same page with 10 October 1781; after 26 October 1781, the bottom half of the page is blank, then entries resume at the top of the reverse side of that sheet with 1 January 1794, page divided into “at sun rise” columns headed “thermom. | Hygrom | Barom. | wind | weather” and “at 4. aclock P.M.” columns headed “therm | hygr | barom. | wind | weather”; beginning 1 May 1794, sunrise and 4:00 PM divisions remain, but with columns in each division for temperature and weather only; hygrometer readings added beginning 25 May 1794, with “DeLuc’s” inserted above header for morning hygrometer readings beginning at 11 June 1794 and on succeeding pages; at a page turn, with no significant gap, entries transition from 30 April 1797 to 26 September 1798; at the foot of a page following the record for 31 October 1799, Jefferson wrote: “see continuation page 91”; the succeeding 22 pp. contain miscellaneous notes; daily observation record resumes with 1 November–18 December 1799, with column headings including specification of “De Lucs” on morning hygrometer readings; on reverse of that page, manuscript ends with 1 p. of miscellaneous notes.

For the period 1 July 1776–10 January 1777, this record duplicates the one from that date range at the Massachusetts Historical Society. To prevent double-counting, the content of entries from this record in that period has been excluded from data visualizations and calculations.

Jefferson marked entries from the afternoon of 13 January 1777 through the morning of 18 January with asterisks and wrote a note at the foot of the page: “observations marked thus * not taken by myself.” Jefferson made a trip to Fredericksburg at that time and apparently had someone else, perhaps his wife, note the temperature at Monticello during his absence. He also put asterisks by the entries from the afternoon of 29 April through the morning of 24 May 1777, when he was on a trip to Williamsburg; the morning of 18 March through the morning of 7 April 1778 (Williamsburg again); and the morning of 12 May through the morning of 13 June 1778 (also Williamsburg; for his movements in these periods, see Memorandum Books, 1:xlvii). For all of those entries, we have recorded the observer as “Jefferson’s proxy.” He also put the asterisk on entries for temperatures in Philadelphia in the period 1–15 August 1777, when he was at Monticello; we have not identified his source for those readings.

Jefferson used vertical strokes to strike through the figures in the columns for afternoon temperature readings from 1 April 1796 to 30 April 1797, and did that also for the morning temperature readings for 22 March to 30 April 1797. He did not explain those cancellations. He similarly struck through morning and afternoon temperature readings from 26 September 1798 through 17 June 1799, except for March and April 1799, which he apparently intended to include in the cancellations but overlooked. In an explanatory note written no earlier than 17 June 1799 but inserted in space on the page following the entry for 17 December 1798, Jefferson stated that temperature readings from all of 1798 and from 1799 through 17 June “are to be rejected” due to the placement of his thermometers (see Note on “Rejected” Temperatures, ca. June 1799). Without providing an explanation, he struck through all afternoon temperature readings for the period 1 July–18 December 1799, but not the morning temperatures.

For all of those canceled temperature readings, the information that Jefferson struck through appears in the transcription in italic type enclosed in angled brackets (< >). Although he rejected the data, the temperatures that he marked out are included in the temperature data field.

At 24 July 1799, Jefferson noted that he was beginning to note dew among weather conditions, signified by the letter “d.”