■ C ;o5 I 



mur, the hygrometer at the fccnnd obfervation ftands nearly at? 

 XCVIH. Oppofite LXXXIV, I find 6^561 in the fecond column, 

 which denotes that 6,561 degrees of cold are required to produce C, 

 but of thefe 6, &c:. 5 have aiSJually accrued ; therefore only 

 6,561 — 5 = 1,561 remaia; and in the fecond column I find this 

 number intermediate between 1, 961 and 1,3.99, ^^^^ nearer to this 

 laft; therefore the eff:(fl produced is folely attributable to cold and 

 not to any new increafe of vapour. — If after the acceffion of five 

 degrees of cold the. hygrometer flood at XCIX, then it would fol- 

 low that as much vapour had been produced as raifed the hygro- 

 meter one degree. — If, on the contrary, on the fecond obfervation 

 it were found, that, after the acceffion of five degrees of cold, the 

 hygrometer flood at only XC degrees, it would prove that there 

 had been fuch a diminution of vapour as counteraded the in- 

 fluence of cold, and would, at the temperature of the firfl ob- 

 fervation, make it ftand eight hygrometrical degrees lower than at 

 firfl. 



The ufe of this table with refpedt to obfervations made at dif- 

 ferent places, in difterent temperatures, and prefenting different 

 hygromeirical degrees, is to find by it in which of thofe places the 

 real quantity of moifture is greatefl. This is found by reducing 

 the temperature at one of thofe places to that of the other, fo 

 that the efFed of mere temperature may be excluded, that thus we 



maj 



