6 EXPERIMENTS ON" 



Although I understand it to ])e this gentleman's 

 intention to give an account of his experiments on 

 these fibres to the pubHc ; yet, as his official calls 

 prevented him from going minutely into the subject, 

 at the period when I had occasion for an hygrome- 

 ter, I was under the necessity of anticipating his 

 intended investigation ; and the cxperin^ents detailed 

 in the appendix will shew, that after an ample trial, 

 the beards of the Panimooloo grass were found per- 

 fectly competent to the construction of an hygro- 

 meter. Three of these instruments were therefore 

 constructed, and the mean of their readings noticed 

 in the annexed tables. 



EXPLANATION OF THE TABLES. 



The detail of experiments on the effects of terres- 

 trial refraction, together with the immediate results 

 deduced from them, appear in these tables, under 

 the appropriate columns ; and a reference to them 

 will best explain their arrangements. 



It is however necessary to explain the meaning of 

 jcertain marks, which appear at various places under 

 the figures, and which have been adopted both for 

 the sake of perspicuity and brevity. 



I soon perceived, after collecting a certain num- 

 ber of observations, the prevailing agreement be- 

 tween the motions of the hygrometer, and the varia- 

 tions, which occurred in the observed angles of ele- 

 vation and depression. 



This being a novel and interesting fact (of which 

 I had still more reason to be convinced, after I 

 had succeeded in regulating the hygrometers) I 

 was desirous to draw the attention on this coinci- 

 dence, and with this view the marks alluded to were 

 affixed. 



