Extract of a Letter from Rome, to M. Maty, M.D. Sec. R. S. on the Extraordinary Heats Observed There This Last Summer

XLIV. Extract of a Letter from Rome, to M. Maty, M.D. Sec. R. S. on the extraordinary Heats observed there this last Summer. Rome, August 27, 1768. Read December 15, 1768. As I remember, when Mr. M— was here, he seemed desirous to ascertain the degrees of heat and cold; I cannot help mentioning the excessive heat of this summer, which is much greater than has been known in Rome for many years. Friday, the 19th instant, the mercury in a well-regulated thermometer according to Fahrenheit's scale, exposed at a North window, where there was no sun and very little reflection, stood from ten o'clock in the morning until about five in the evening at ninety-nine. About half an hour after sunset it fell to ninety, and at midnight was fallen to eighty-five, where it remained all night. This is the hottest day we have had, but for these three weeks past at midday the mercury has been always above ninety-four, and at midnight seldom under eighty-three, which is the more extraordinary as I do not remember to have observed any other summer above eighty-nine at midday, nor above seventy-five at midnight. Notwithstanding this great heat, there was never a more healthy summer at Rome; all the hospitals are almost empty. James Byres. XLV. An