^16 OBSEBVATIONS ON THE MEAN TEMPERATUBE 



By applying this last Formula to the results obtained by 

 Humboldt, and to the observations of Captain Scoresby and 

 Captain Parry, we shall have the following observed and cal- 

 culated temperatures * : 



The differences in the fourth and seventh columns are far 

 from being considerable ; and when we reflect upon the uncer- 

 tainty in the position of the Poles, and the range of the annual 

 temperature at any given place, the coincidence of the obser- 

 ved and calculated results is greater than could have been ex- 

 pected. 



In the preceding comparison, the places to which the mean 

 results belong, are supposed to be situated either in the warm 

 meridian which passes through the west of Europe, or in the 

 cold meridian which passes through North America. In com- 

 paring, however, the theory with observation, we shall proceed 

 to put it to the severe test of contrasting it with observations 

 made in intermediate meridians, both in the Old and the New 



World ; 



^ -rv Cos. i (Cos. L — «) , 



In all intermediate meridians we have Cos. V — Cos"! ' 



Tan". 6 = Cos. M. Tang. L, where M is the difference of longitude between the 

 place and the Pole, L the co-latitude of the Isothermal Pole or 10°, and / the co- 

 latitude of the place. 



* The calculation for the Old World is founded on the supposition, that the 

 meridian to which the mean results of Humboldt belong is at right angles to the 

 ccld meridian in 100° West Longitude. The greater number of places, however, 

 from which the mean was taken, are nearer the Asiatic than the American Pole 

 Hence we see the reason why the differences are all positive. 



