Note on “Rejected” Temperatures, ca. June 1799

From Daily Record, 1 July 1776-18 December 1799 (Library of Congress).
In Jefferson’s hand, inserted in space on the page following the entry for 17 December 1798, but written 17 June 1799 or after.

Note. all the thermometrical observations of the year 1798. & those of 1799. to June 17. inclusive are to be rejected. during that period my thermometer had been placed in the N.E. portico, newly built, and it was not till June 17. 99. that I discovered it to be artificially heated, probably by the mound of earth in it. I then removed the 2 thermometers to approved positions.