Prof. Schouw on the Climate of Europe and Africa. 151 



4. The difference of the temperatures of the seasons, and 

 of the months, augments not only from the equator towards 

 the Polar Circle ; but, in the portion of the globe under consi- 

 deration, it likewise increases from west to east, i. e. from the 

 coast of the Atlantic towards the interior of the continents. 



5. Between 60° and the Tropic of Cancer, the hottest months 

 of the year occur at a later period in proportion as the geo- 

 graphical position is more northern. 



G. In the same latitude the hottest months occur at a later 

 period in proportion as the sea is approached. Thus in com-, 

 paring the months of June and September we have, 



HyeiograpJiical Conclusions, 



The zone of summer rain extends in Africa from the equator 

 to the 15th degree N. latitude. The quantity of pluvial water 

 is very considerable, but the rains do not fall except in the 

 months of northern declination of the sun. 



The zone tcithout rain includes Northern Africa, between 

 15° and 30° N. It is the zone of deserts, and is either entirely 

 devoid of rain, or the rains are very rare, and entirely acci- 

 dental. 



The zone of winter rain includes Northern Africa and South- 

 ern Europe, between 30° and 45° N. latitude. The rains are 

 almost confined to the months of low temperature (in the 

 southern portion of the zone), or they are very frequent in 

 these months, and rare in those of an elevated temperature. 

 The quantity of pluvial water augments towards the Atlantic, 

 but still more towards the mountains; above all, it is very 

 considerable on their northern and western slopes, but very 

 small on the plateau of the Spanish peninsula. 



The zone of continued rain includes the portion of Europe 

 between 45° and 60° N. The aqueous prccipitationiS are fre- 



