Meteorological observations and essays / By John Dalton.

  • John Dalton
Date:
1834
Catalogue details

Licence: Public Domain Mark

Credit: Meteorological observations and essays / By John Dalton. Source: Wellcome Collection.

    120/280 (page 94)
    latitude 37° 20’ N. the annual range is above one inch, which is the same as at Genoa, latitude 44° 25’ N. 6. In the temperate zones the mean state of the barometer in the summer months is nearly equi- distant from the extremes in that season; but in winter the mean is much nearer the higher extreme than the lower. According to the observations at Kendal (see page 15*) the mean height of the barometer in July is distant from the higher extreme .33 of an inch, and from the lower extreme .37; in January the mean is distant from the higher extreme .79, and from the lower 1.17: the ratio of the former distances is as 11 to 12, and of the latter as 8 to 12, nearly. Professor MusscHENBROEK, in his Elements of Natural Philosophy, (translated by Cotson,) pub- lished about 50 years ago, has endeavoured to ac- count for those changes of weight in the atmosphere ; he has adverted to all or most of the causes that have ever been considered as agents in producing the effects: he enumerates the following causes, namely; First, the opposition of winds; second, the north wind blowing, which cools and condenses the air ; third, the winds blowing upward or downward ; fourth, an increase or diminution of heat, which rarefies or condenses the air, in consequence of which the air’s distance from the earth’s centre is increased or diminished, and its weight, as well as centrifugal force, thereby affected ; fifth, the air * The mean for July, uncorrected, is 29.77, and for January 29,66, which must be used in this case, because the extremes are not corrected.