[ 3^3 ] 



mountain, Of other height fought, gives the di.Tjinution of "heat at: 

 that height; and tliis diminution fubftraded from the heat below, 

 gives the degree of heat that obtains at the propofcd height. 



EXAMPLE. 



In latitude 56*^. 30', the heat below being 5^).°, it is required to ■ 

 know the diminution, and the degree of heat that prevails at the 

 height of 1364 feet ?. 



Here. the latitude being intermediate between latitude 0" and 

 57^, the height of the upper line of congelation is the mean be- 

 tween 5533 and 54.39 — 5486 feet, then the divifor is 53,86 terms, 



and the dividend is 54^_':2° = 22, and — ' =,408, the 



53^86 



common difference. Now 0,408 x 13)64 ^=5,5 the diminution, and 



54_ 5,5 = 48*^,5, the degree of heat which prevails above; which 



is exadly that obferved by General Roy at the fummit of Knock- 



farle in Scotland. Phil. Tranf. 1777, the heat below being 54°, 



and the height 1 364 feet. 



In this manner I have calculated the heats at various heights in 

 various latitudes, the degrees below being given, the refults both 

 by obfervation and calculation may be feen in the annexed table. 



Table 



