ISOTHERM OF 20°. 139 



lines. The isothermal charts, which have been 

 designed from these,* exhibit at one glance the 

 great divergence of the lines of equal mean tem- 

 perature from the parallels of latitude. I subjoin 

 some instances, by following which, on a good 

 map of the world, you will obtain a tolerably clear 

 view of this remarkable relation. 



The isotherm of 20° Cent. (68 Fahr.) cuts the 

 west coast of Africa to the south of Mo gad or, it 

 then rises towards the Mediterranean Sea, passes 

 to the south of Algiers (19°*6 C), runs along the 

 coast of Tunis (20 o, 3), to Cape Bon, then run- 

 ning to the south of Sicily, Candia, and Cyprus, 

 crossing Syria between Damascus and Jerusa- 

 lem, and rising gradually towards the north, it 

 passes south of the Caspian Sea at Teheran, and 

 over the table-land of Iran, verging southwards 

 till it falls on the eastern coast of China, in the 

 latitude of the Loo-Choo Islands. It reaches 

 the peninsula of California, 28° N, and it then 

 soon turns again more towards the north, and 

 runs along the 32nd parallel through Texas, 

 Louisiana, Mississippi, Alabama, and Geor- 

 gia (Savannah, 19°'5) to the Atlantic; hence to 



* These may be seen in the "Physical Atlas" of Berg- 

 haus, or in the English edition, by Johnston and others, 

 or in Dove's well-known charts, 



