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.

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    rometer, etc.” published in the Philosophical Magazine, as already stated, is first given, followed by these remarks :— “ Such was the state of my information on this subject twenty years ago (or in 1799). The study of the modifications of clouds, and the various phsenomena con- nected with them, afterwards occupying my attention, this particular enquiry was suspended: and when, in 1806, I began to keep a regular Meteorological Journal, it was with more general views. But being still desirous of putting to the test the opi- nion of a Lunar tide in the Atmosphere, I was induced, as already mentioned, to digest the observations in the form which seemed to afford the greatest facility for this purpose. It remains to show how far the purpose was fulfilled. “ Plate I. exhibits, in a system of curves, the variation of the daily mean height of the Barometer through the Polar year 1806-7.” They are constructed from observations of the Barometer, stated in inches and hundredths, in Tables II. to XIV. inclusive, of the “Climate of London,” which are part of those Mr. Howard first published monthly in the magazine entitled the Athenaeum*. The periods, however, are differently arranged. In the Tables they begin at the New Moon; but for the curves, in order to show more evidently the influence of New and Pull Moon, the periods are “ made to begin with the day of the third quarter; which happens in this instance to be the first day of 1807. After a dotted curve, therefore, giving the variation from Dec. 22, 1806 to the end of that year, the several curves a—b, b—c, &c. carry on a series of entire Lunar periods to the 21st of Dec. 1807, at n, where the Solar year closes.” These curves were constructed in the following manner : the mean of the period was ascertained by calculation, and represented by a horizontal line. The relation of the mean of each day to this standard line was next ascertained and marked; and a curve carried through the points thus found, represented the variation, at its proper extent, above and below the standard. In doing this the mean of the day on which a Lunar phase happened, was made always to fall in the intersection of the curve with a perpendicular line appropriated to that phase. Some inequalities of time in the intermediate parts of the curve, occasioned by this arrangement, were remedied, where needful, by using an unequal scale of time in those parts. “ By this method [in concert wif.h the late Silvanus Bevan, Jun.] the curves were all obtained of an equal length, and presenting equably the relation of the Lunar points to the Barometrical mean for the period. Their tendency to rise and fall at particular intervals, and their consent or opposition in such movements, was thus also repre- * An account of the original publication of Mr. Howard’s Meteorological Observations will be given in a future Section.