Daily Record, 25 July-14 August 1792

Owned by Roger W. Barrett, Chicago, Illinois, 1947.

2 pp., front and back of a scrap of paper (images are from a photostat made in 1947).

This record consists of a table in which Jefferson listed morning and afternoon temperatures and abbreviated notations of conditions at Monticello, 25 July–12 August, and at Philadelphia, 25–31 July and 8–12 August. He did not note the year. The information for Monticello matches that for the same dates of 1792 in the 1 January 1791–9 April 1794 record at New York Public Library. Jefferson, who was at Monticello in the summer of 1792, obtained the Philadelphia data from the 1 August and 15 August 1792 issues of Philip Freneau’s newspaper, the National Gazette. The newspaper did not name the person who made the observations in the “Meteorological Chart” it published regularly. As shown by a postscript to a letter to David Rittenhouse on 12 August, Jefferson knew that Rittenhouse was the source. “Before sealing my letter I received Freneau’s paper of the 1st. inst.,” Jefferson wrote, “and cannot avoid giving you an extract from my Diary corresponding in time with yours in that paper.” Jefferson then transcribed in his postscript the Philadelphia and Monticello data for 25–31 July. According to the tables published in the newspaper, Rittenhouse’s observations were made at 6:00 AM and 2:00 PM. Jefferson, as he indicated to Rittenhouse, made his observations at Monticello “about 6. A.M. and 3. to 4. P.M.”

To prevent double-counting, the Monticello entries from this record have been excluded from data visualizations and calculations.