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.

    225/280 (page 199)
    From occasional breaks in this stratum I could see a third and still higher stratum of very light, fleecy clouds, moving in the same direction, and probably with the same velocity as the other two strata, but apparently much slower, on account of their greater elevation. I judged them to be about three times the height of the lowest stratum, or rather more than a mile. There was thunder this day at Man- chester, and other places in the north of England. No person can have an adequate knowledge of clouds but one who has been above them, and in them, as well as below them, in calm weather, in windy weather, in summer, and in winter. This has been my lot frequently. Visiting the moun- tainous parts of Cumberland and Westmorland annually, and generally ascending one or more of the highest mountains, I had various opportunities of investigating the nature of clouds, especially in summer. Enveloped in a fog on the summit of a mountain in summer, one may see to read, or view divisions on an instrument, or in short any object within two or three yards, but all beyond that dis- tance is hid in impenetrable darkness. ‘The sum- mer fogs are much more dense than the winter ones which we have on the plains. In these one may often see houses, trees, &c. at the distance of ten or twenty yards; but the former are usually much more dense. Notwithstanding this greater density of the vapour, in a strong wind the mass of vapour is evidently moving with the velocity of the wind. To most people there is somewhat of novelty in