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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    which they occur.” I had thus carried the inquiry into three years of my own and two of Mr. Cumming’s observations; and it regarded the barometrical variation alone : I have now extended it to a cycle of nine years, and made it include the other phaenomena of temperature and rain, dependent in like manner, in this climate, on the direction of the wind: the following results will be found, I apprehend, of sufficient importance to claim the notice of the Society in addition to those I have already submitted to it, on the connexion of these several phaenomena, in their periods and extent of variation, with the moon’s phase*. 1. The barometer is higher under the apogee than under the perigee : the cases in detail in which this occurs in the Tables, are as 66 to 48—the number of pairs of apsides examined being 114: the seven apsides not standing apposed to each other in the Tables afford on comparison the same result. The variation of the mean height proceeds under each apsis to the same extent, viz. about T58 inch; but the larger range belongs on the whole of the nine years to the perigee—the mean variation being then, apogee 0 9883 inches, perigee 1T761 inch. Of the nine yearly mean results, standing in the Summary at the end of these Tables [p. 28a opposite], seven agree strictly with the ride. The year 1821 is an ex- ception, to be further noticed : 1823 agrees as it stands, summed up with two pairs of apsides included, that overpass the cycle; but with these left out, we have apogee 29 6995, perigee 29 7780 inches, the exception going to nearly the same extent as in 1821. Of this last year, in which the height at the perigee exceeds (instead of falling short) by a tenth of an inch, I may remark that the difference in favour of the apogee in 1820 is extreme, amounting to a third of an inch (the mean of this apogee being also the highest, and that of the perigee the lowest of the series); and that if we take a mean betwixt this and the deficient one following (in 1821), we shall have a result agreeing with the rule—and the like of the perigee in each. There was therefore some peculiar cause influencing to a great extent the density of our atmosphere in that season, whch may be made the subject of further inqmry in another place. But the result on which I place the greatest dependence in proof of my main pro- position, is the mean for each apsis of the whole of the observations included in the cycle, which is for the apogee 29 84517 inches, for the perigee 29 75542 inches, the apogee here exceeding by '08975 inch. 2. The mean temperature is lower under the apogee than under the perigee. The range of the mean proceeds, as before, to the same extent under each apsis ; but on [* P. 19“ of the present collection.]