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.

    118/280 (page 92)
    ESSAY THIRD. On the variation of the Barometer. Tue causes of the variation of the barometer have never yet been discovered, so as to admit of demon- stration ; though several eminent philosophers have eiven the public the result of their reasoning and experience on the subject. We propose to consider the principal of their allegations; but in the first place it will be proper to lay down the chief facts respecting the variation, which are the result of observation, and not of any hypothesis. Facts relating to the Barometer. i. The barometer has very little variation within the tropics. I believe the barometrical range has not been observed much to exceed half an inch, in the torrid zone. 2. Within the northern temperate zone, and doubtless the southern also, the range of the baro- meter increases in going from the equator. The mean annual range* at Paris, in latitude 48° 50’ N. for 20 years, was 14 inch; the greatest range, or difference between the highest and lowest observations, for the same term, was 2 * By annual range I mean the difference between the highest and lowest observations each year.