so DESCRIPTION OF 



divisions continued to the number denoting extreme 

 dryness. 



If the whole of that part of the Oobeena hooloo, which 

 possesses the hygroscopic property he used, the scale 

 \vi\\ comprize more than txventy-Jour inches, a length, 

 which, though perhaps useful on particular occasions, 

 will not be found convenient for general purposes. 



From an idea, that in a high state of moisture, the 

 grass would not retain sufiicient power to move the 

 wheel equably, it was thoroughly wetted, till it indi- 

 cated extreme moisture, and, while in this state, the 

 wheel was drawn round , by laying hold of one of the 

 threads : on releasing it, it instantly regained its for- 

 mer situation, with considerable force. The same 

 experiment was made, in various other states of mois- 

 ture, and it was always found, that the weights re- 

 turned immediately to the degree from which they 

 had been removed. 



It would perhaps be an improvement, if a light 

 wheel, of brass, or any other metal, not liable to rust, 

 were used instead of the ivory one; the grass having 

 been found, by experiment, to be capable of moving 

 a wheel of lead. The axis of the wheel might be 

 made very small, and supported on Ys, which proba- 

 bly would add much to the sensibility of the instru- 

 ment. 



I have as yet had no opportunity of comparing this 

 with any other hygrometer; but it is simple in its 

 construction, not easily disordered, and should seem, 

 fjoui the extent of its scale, to be particularly adapted 

 to experiments, in which small variations of moisture 

 are to be observed. 



The hygrometer has been hitherto an instrument, 

 rather of curiosity than utility. But from most 



