250 On the Mean Temperature of the 



where a and b are constant, I the latitude, and t the terrestrial 

 temperature. 



Let us combine, in the first meridian, to find out the constant 

 numbers, the observations of Paris and Edinburgh. We obtain, 

 a — 6 sin^ 56° = 47°.75, 



a — 6sin2 49° = 53°.37; 

 from which 



a = 79°.92, b = 47°.02. 



The following Table gives the comparison of the observed 

 and calculated values : 



The observation at TenerifFe deviates very much ; but this 

 island lies very far west, and consequently not properly un- 

 der the first meridian. 



In like manner, for the second meridian, if we use only the 

 observations of Cairo and Upsal, 



a = 86°.9, b z= 5T.6. 

 These values give the following Table : 



For the third meridian, we find, from the observations of 

 Kiskencjewa and Bogoslowsk, 



a = 83°.52, b = 6l°.87. 



