Description of a 7ietu Anemometer. 247 



the altercations which he had with his commissioners, and 

 with others ; which now renders the reading of it very te- 

 dious. Nevertheless, had he only given this work, and 

 the two inventions we have just mentioned, he would have 

 deserved to be reckoned among those who hy their works 

 have contributed to the advancement of the sciences, and 

 consequently to the cause of humanity. If it is not very 

 interesting for the public to know who is the author of a 

 discovery, of which they enjoy the benefit, it is of great 

 importance that discoveries should be made ; and the most 

 certain means of increasing them, is to render full and en- 

 tire justice to the authors. The reception given to their 

 works is the most flattering part of their recompense; and 

 :t is to be wantino; in <rratitude to deprive them of it. 



° ° E. 



XXXIV. A Description of anew Anemometer. JBy Richard 

 KiRWANj Esq., LL.'D. F.R.LA. F.R.S. &c. @c.* 



JL HAT rain, on the presence or absence of which at the diffe- 

 rent seasons of the year, vegetation, and the success of agri- 

 cuhure, in great measure depend, and also the temperature of 

 the atmosphere, to whose influence both animals and vege- 

 tables are subject, arises from, or at least is strictly con- 

 nected with, the various directions and velocities of winds, 

 is well known. Nor has it escaped observation, that the 

 primary cause of the direction of the wind from a given 

 quarter, as well as of the velocity of its progress, is the rare- 

 faction of the atmosphere in that tract towards which it 

 blows. The reason why air does not rush in from all sides 

 towards the rarefied tracts, seems to me to be the inequality 

 of its density in the surrounding tracts ; jfor from that quar- 

 ter, in which the mercury in the barometer stands highest, 

 the air niust preferably proceed. If the density be equal on 

 all sides, as in some confined tracts, a hurricane happens : 

 hence the advantage of ascertaining and comparing the de- 

 grees of its velocity ; for, those beine known, its cause and 

 degrees of rarefaction may with great probability be infer- 

 red. Two causes of rarefaction are already known, — solar 

 heat, and some internal chemical action, by which a quan- 

 tity of air is converted into waier, and sometimes even into 

 a stony substance; this last being the most sudden and 

 complete, the rarefaction of the neighbouring air arising 



• I'Vom »lic TranMction! of the Royal Irish Acadtniy, Tor ItiOS. 



O 4 from 



