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

  • Luke Howard
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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    these latitudes, in declination, in 1807 and 1816, the winds from the West and North-west fell off in number. Now if we consider that the Moon’s daily course from East to West (which though only apparent has here the same effect as the real,) was coupled, during these weeks, with a motion from South to North in declination, it will appear that a South-east wind would now, in effect, follow her course, and a North- west flow in opposition to it. And in 1816, during the weeks in which the Moon was receding in declination to the Southward, and thus offering daily less and less resist- ance to a North-west wind, this class of winds amounted to double the number which they exhibited in the former case. Again, in both years, and especially in 1807, the class of winds from North to East, which are plainly most influenced by the Sun, appeared in the greatest number while the Moon was in Full South declination, and when consequently there was little of the rarefaction, which she is here supposed to produce, in these latitudes. “ The succession and proportion of the winds are consequently subject to a peri- odical variation from year to year: but the period in which the same or a similar set of winds comes around again, cannot at present even be conjectured. From the effects produced in our [London] district, on the average temperature of the years, and on the depth of rain, it may seem to have some connexion with the Lunar cycle of 18 years. But this is a subject well worthy of separate and more deliberate investigation*.” In the “ Summary” of results in the order of the seasons, as presented by the climate of London, near the conclusion of the work, Mr. Howard observes,—“It is demonstrable, from abundant evidence, (enough of which is even contained in this volume,) that we owe most of our vicissitude, even in temperature, to the Moon. It appears that our attendant planet, principally, if not solely, by the effect of gravity, continually disturbs the density of the atmosphere, producing, in the temperate latitudes of the globe, a variety of currents, the different qualities of which, in respect of temperature, moisture, and electricity, are developed as they successively pass over. Hence great variety of weather;—this, however, on the great scale of the year, is regulated by the more or less predominant influence of the Sun, according to his place in declination: which secures to us the enjoyment of our four seasons in suc- cession, these minor fluctuations notwithstanding. “ I have shown that the great fluctuations in the density or gravity of the atmo- sphere, in our climate, are principally due to our participation, by turns, of the Polar * The results of the investigation here contemplated are given in Section III., and in the paper commencing at p. 43a.
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