Papers on meteorology : relating especially to the climate of Britain, and to the variations of the barometer / by Luke Howard.

  • Howard, Luke, 1772-1864.
Date:
1850-1854
Catalogue details

Licence: Public Domain Mark

Credit: Papers on meteorology : relating especially to the climate of Britain, and to the variations of the barometer / by Luke Howard. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    9/174 (page 5)
    In October 1801 Mr. Howard communicated to Dr. Tilloch for insertion in the Philosophical Magazine a translation, with which he had been supplied, of a paper “ On the Influence which the Sun has on the State of the Barometer,” by J. J. Hem- mer (who was the Secretary of the Meteorological Society of the Palatinate), which had appeared in the Transactions of the Electoral Academy of Sciences at Erfurt, vol. vi. This was published accordingly in the Philosophical Magazine for November 1801 (Eirst Series, vol. xi. p. 151-157). On this paper Mr. Howard remarks, in a prefatory letter, “ It is another proof (which I was not possessed of at the time my essay on the same subject appeared) of the attention which this question had ob- tained on the continent; and as, notwithstanding a considerable similarity in the introductory part, our inquiries appear to have been directed to distinct though closely-connected branches of the subject, each of these papers may prove to the reader a useful commentary on the other.” To a passage in Hemmer’s paper (p. 153), relating to observations of the diurnal or horary variations of the barometer made severally by Planer and Chiminello, two members of the Meteorological Society of the Palatinate, Mr. Howard subjoined the following note: “ In examining a twelve-month’s Register, kept by — Dunbar, Esq., near the banks of the Missisippi, in N. lat. 31° 28', and long. 91° 30' West of Greenwich, which, for the greater facility of comparison, I have laid down, with others, on a scale in the manner I have heretofore exhibited, there occurs a remarkable instance of a diurnal variation. Por the space of about four days before, and six days after the summer solstice, the barometer regularly rises from about 9 p.m. to about 6 a.m., then falls till the return of the former hour in the evening, then rises again as before, &c. in alternate periods. In the first four days the direction is ascending, and the elevation of a line drawn through the mean is about ywoths of an inch. In the latter six days the mean line is perfectly horizontal, the elevation each night amounting to yfy^ths, and the depression each day to the same, but occupying double time. The times above given are those at which the observations were made, but it is probable that the maximum and minimum each day corresponded rather with the times of sun-rise and sun-set. The first period of four days was dry, with a temperature of 92° in the middle of the day. This ended in a thunder-storm, on the 21st of the month, with 0-82 inches of rain. The barometer, after this, rose y^ths in the night, then re- mained mostly stationary, with cloudy weather, until the evening of the 26th [of June, 1800], beginning a second period of six days, during which brisk winds at S., S.E., and S.W., prevailed with rain every afternoon or evening, amounting, in all,