HYGKOLOGY, AND ITS CONNECTION WITH METEOROLOGY. QQS 



suspended very thin shavings of the same substances as the 

 enclosed hygrometers ; 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 j 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 m length continue to imbibe 

 moisture, though they cease to lengthen, and some even begin 



to shorten. 2. That slips cut across the Jilres continue to 

 lengthen so long as the moisture increases, 3. That the slip of Whalebone 

 whalebone follows very nearly in its lengthening the rate of 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- Theinstru- 

 vered my papers to the Royal Society j thus concluded by the nient httle 

 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 ; but after he 

 had sold a few, he,vvas engaged to go to Portugal, with a pen- 

 sion from the government ; and since that time, no other instru- 

 ment-maker had undertaken to construct it. But lately a Hano- I'lit now may 

 verian gentleman, Mr. Hausmann, who lives now at Cumber- ^ ""t>^* 

 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 



, . T I 1 , 1 • J • ^1 I of water in air 



these experiments, I had only obtained a raiio between the answering to 



quantilies 



