On hygrology, hygrometry, and their connexion with the phenomena observed in the atmosphere / by J. De Luc.
- Luc, J. A. de (Jean André), 1727-1817.
- Date:
- 1812
Licence: Public Domain Mark
Credit: On hygrology, hygrometry, and their connexion with the phenomena observed in the atmosphere / by J. De Luc. Source: Wellcome Collection.
Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.
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![suspended very thin shavings of the same substances as the enclosed hygrometers 5 which shavings indicated, by the increase of their weight, the weight of the water which pene- trated them. I had a lime-vessel by which I first produced extreme dryness in the vessel containing the instruments $ and when I had observed them in that state, and taken off the vessel containing the lime, I had also a manner of increasing moisture by degrees in that of the instruments, observing at each step the motions of the hygrometers, and the increase of weight of the shavings. 10. The general results of this experiment were the follow- Results, ing :—1. That substances taken in length continue to imbibe moisture, though they cease to lengthen, and some even begin to shorten. 2. That slips cut across the fibres continue to lengthen so long as the moisture increases. 3. That the slip of Whalebone 11, r 11 , . . , , . ' . preferable, whalebone follows very nearly in its lengthening the rate ot the increase of moisture, indicated by the increase of weight in its shavings. From this last result, and from the great elasticity of this substance, which makes it always sensibly return to the * same length with the same degree of moisture, I fixed on a slip of whalebone for my hygrometer. 11. Such was the point which I had attained, when I deli- The instru- vered my papers to the Royal Society; thus concluded by the determination of an absolute and comparable hygrometer, which was wanting in the set of meteorological instruments commonly observed : but by an unlucky circumstance, it still remains little known, and thus enters very seldom into the considerations concerning meteorological systems. I had di- rected, in the construction of that instrument, a very able Ger- man instrument-maker in London, Mr. Haas 5 but after he had sold a few, he]was engaged to go to Portugal, with a pen- sion from the government 5 and since that time, no other instru- ment-maker had undertaken to construct it. But lately a Hano- but now may verian gentleman, Mr. Hausmann, who lives now at Cumber-^ou§^lt' land lodge, near Windsor, seeing that it was a very important instrument for meteorology, has undertaken its construction, and having succeeded, he is disposed to make it for those expe- rimental philosophers, who may wish to have it. 12. So far, however, as may be seen in the above account of The quantity these experiments, I had only obtained a ratio between the aLweriii^t©51 quantities](https://iiif.wellcomecollection.org/image/b2851984x_0009.jp2/full/800%2C/0/default.jpg)
