The temperatures which Dr. Heberden wishes to record in this paper, are those observed on the 15th, 17th, 18th, and 19th of last July, and were respectively 92°, 90°, 96°, and 95°. On the 15th, the wind was S.W ., on the other days it blew from the East. The thermometer employed was sensible and accurately graduated, and was suspended upon a lawn, about 5½ feet from the ground; on the first day, in the shade of a laburnum tree, and afterwards from an external branch of a large Portugal laurel; always distinct from any building; exposed to the full influence of the wind, and at the same time sheltered from the actual rays of the sun, and from substances heated by them. The author adds, that the only instance on record of a corresponding elevation of atmospheric temperature was in July, 1808; on the 13th of which month, it appears from the Royal Society’s register, the thermometer rose to 93°.5, and Mr. Cavendish’s thermometer, at Clapham, to 96°. By way of comparison, Dr. Heberden observes, upon the authority of the late Dr. Hunter, that in the hottest season, and during the hottest part of the day, the range of the thermometer, at Kingston, in Jamaica, is from 85° to 90°. To these remarks, Dr. Heberden adds some observations on the imperfection of the thermometer, as a measure of the degree of cold perceptible to the human body in its ordinary exposure to the atmosphere, and which depends upon the rapidity with which its own heat is carried off by the conducting power and currents of the atmosphere. To estimate this insensible cold, the author raised the thermometer to 120°, and then carried it into the open air. As soon as the mercury had fallen to 100°, the rate of its further descent, during every 10'', was noted for half a minute, in different states of the atmosphere in regard to wind and moisture. These experiments, which are given in the form of tables, show the powerful effect of wind in increasing the rate of cooling, and consequently of exciting the sensation of cold in the human body, independent of any actual low temperature of the atmosphere.