Licence: Public Domain Mark
Credit: Meteorological observations and essays / By John Dalton. Source: Wellcome Collection.
56/280 (page 30)
Licence: Public Domain Mark
Credit: Meteorological observations and essays / By John Dalton. Source: Wellcome Collection.
![S EiGGLON? WH] RD: Of the Hygrometer. Tue hygrometer is an instrument meant to show the disposition of the air for attracting water, or for depositing the water it has in solution with it. Some of the greatest philosophers of the present age have been endeavouring to improve those in- struments of this description we have already, and to invent others less objectionable ; but I presume the object is not yet fully attained.—To ascertain the exact quantity of water in a given quantity of air, and also the disposition of the air for imbibing or depositing it, is an object indeed highly impor- tant to the science of meteorology, and to philoso- phy in general. -It does not suit our intended brevity to enter into a detail of the different instruments lately proposed, with their respective merits and de- merits; we shall only observe, that most sub- stances are affected more or less with the dryness and moisture of the air, particularly animal and vegetable fibres, which become turgid, and con- tract by being exposed to moist air. Sponge, paper, &c. imbibe moisture, and become alternately lighter and heavier by being exposed to the air. Strings, whether made of animal or vegetable](https://iiif.wellcomecollection.org/image/b33286218_0056.jp2/full/800%2C/0/default.jpg)
