Remarks upon the Heat of the Air in July 1757. in an Extract of a Letter from John Huxham, M. D. F. R. S. to William Watson, M. D. F. R S. Dated at Plymouth 19th of That Month. With Additional Remarks by Dr. Watson

LIV. Remarks upon the Heat of the Air in July 1757. in an Extract of a Letter from John Huxham, M.D. F.R.S. to William Watson, M.D. F.R.S. dated at Plymouth 19th of that Month. With additional Remarks by Dr. Watson. Read Dec. 22, "FROM the beginning of June last 1757. "we have had a very dry season, generally very warm, and sometimes excessively hot. From the 7th to the 14th of this month the heat was violent; greater, indeed, than has been known here in the memory of man. I have talked with several persons, who have lived a considerable time in Jamaica, Gibraltar, and Minorca; and they feverally assert, that they never felt such intense heat in any of those places. Upon the 11th, 12th, and 13th of this month, Fahrenheit's thermometer, in the shade, about three o'clock in the afternoon, was at 87; nay, upon the 12th it was even above 88. "Abundance of people have suffered very severely from these excessive heats: putrid, bilious, pectial, nervous fevers, are exceedingly common every-where. Dysenteries, haemorrhages, most profuse sweats, affect not only those in fevers, but a vast many others. The days and nights were so intolerably hot, that little or no sleep was to be gotten day or night. The wind we had, like the Campsin, actually blew hot, tho' strong. "Upon "Upon the 15th, about seven at night, at Fal- mouth, Penryn, Truro, and thereabouts, a pretty smart shock of an earthquake was felt, attended with a hollow rumbling noise, throwing down pewter, china-ware, and such-like. The tinners felt it eighty fathom under ground. No great damage however was done. The day before we had, about eleven o'clock before noon, a most violent hurricane, which lasted five or six minutes, attended with a heavy shower." Thus far Dr. Huxham. The heat of the air at London, during the period above-mentioned, was much greater than has been usually observed in these high latitudes; tho' it was never quite so severe here as at Plymouth. The fol- lowing table exhibits the degrees of the heat, taken here upon the respective days, about four o'clock in the afternoon, by a Fahrenheit's thermometer. The instrument was placed in the shade; and the accuracy of the observer, who favoured me with his minutes, is not to be questioned. | Date | Temperature | |------|-------------| | July 5 | 75 | | 6 | 78 | | 7 | 75½ | | 8 | 78 | | 9 | 80¼ | | 10 | 83¼ | | 11 | 80¼ | | 12 | 80 | | 13 | 85 | | 14 | 81 | | 15 | 73 | From From hence it appears, that the air at London was, upon several days, hotter than it had been observed at Madeira for ten years together: for, by Dr. Thomas Heberden's observations, mentioned in the Philosophical Transactions, the heat of the air at Madeira, during that period, was never but once at 80. William Watson. LV. Remarks upon the Letter of Mr. John Ellis, F.R.S. to Philip Carteret Webb, Esq; F.R.S. printed in the Philosophical Transactions, Vol. xlix. Part ii. p. 806. By Mr. Philip Miller, F.R.S. Read Dec. 15. 1757. The paper of mine, which was read before the Royal Society on the 8th of May 1755, and afterward printed in the xliith volume of the Philosophical Transactions *, was written at the request of Mr. Watson; who informed me, that a letter from the Abbé Mazeas to the reverend Dr. Hales had been communicated to the Royal Society, in which it was mentioned, that the Abbé Sauvages had made a discovery of the juice of the Carolina Toxicodendron staining linen of a permanent black. But Mr. Watson said, that the letter, he thought, required a careful perusal before it was printed; and he wished I would confirm it. I told * Part I. p. 161.