242 Dependence of the Geographical Relations of Countries 



to 3° R. (2° to T F.), by which the temperature of woody 

 cjountries stands lower. A comparison of France and tke 

 Netherlands with Hungary, Bohemia, Bavaria, Austria, and 

 Prussia, regarding their climate, renders that difference more 

 manifest ; and a parallel drawn between France and western 

 Russia, or also between France and Louisiana, Guyana, and 

 the United States of North America, gives a balance of from 

 2^ to 6^ R. (41° to n° F.). 



These facts are still more strongly illustrated by the depres- 

 sion of the isothermal lines in woody countries, and by their 

 elevation in those destitute of forests. In the former they 

 descend further towards the equator, in order to attain the 

 same mean temperature, because forests tend to diminish heat 

 as well as cold ; the isothermal lines mount, therefore, higher 

 up in the latter. The isothermal line of 8° R. (50° F.) ascends 

 in the Netherlands beyond lat. 53*^ ; in Rhenish Prussia, and 

 the two principalities of Hesse, it descends as far as 50^° ; it 

 then rises in the north of Germany a little beyond 52^^, and 

 sinks again in Saxony, Bohemia, and Gallicia, down to lat. 

 49° ; because, these countries being well stocked with forests, 

 less latitude is requisite in order to compensate the depression 

 of the mean temperature which is owing to the forests, by a 

 more southerly situation. 



The isothermal curve of 10° R. (54|° F.) begins in the west 

 with lat. 47° ; rises in France, between the Loire and Seine, 

 nearly as far as 48°, because that district is almost completely 

 stripped of wood ; but afterwards it sinks again between the 

 Seine, the Moselle, and the Rhine, and in French Switzerland, 

 as far as 45^°, preserves an oblique direction throughout the 

 whole of southern Germany, Hungary, and Transylvania, 

 until, in Wallachia, it falls as low as lat. 44°. The depressions 

 plainly indicate the woody countries — the eastern provinces of 

 France, Switzerland, the whole of southern Germany, and 

 Hungary ; the elevations again point out the woodless coun- 

 tries : so that the results obtained from our comparisons attri- 

 bute a difference of 1° to 2° (2°.25 to 4°.50 F.) in the mean 

 temperature to the intervention of forests, scattered over 

 the different countries in Europe ; whilst in America, which is 

 densely covered with wood, that difference amounts to 4° (9° F.) 



