296 THE PHYSICAL GEOGRAPHY OF THE SEA. 



5-i6. In the Mediterranean, tlie evaporation is greater than tlie 

 The Mediterranean precipitation. Upon tlie Ked Sea there never falls 

 within it. ^ drop of rain ; it is all evaporation. Are we not, 



therefore, entitled to regard the Ked Sea as a make- weight, thrown 

 in to regulate the proportion of cloud and sunshine, and to dis- 

 pense rain to certain parts of the earth in due season and in prop- 

 er quantities ? Have we not, in these two facts, evidence conclu- 

 sive that the winds which blow over these two seas come, for the 

 most part, from a dry country — from regions which contain few 

 or no pools to furnish supplies of vapor ? 



547. Indeed, so scantily supplied with vapor are the winds 

 Heavy evaporation, which pass in the general channels of circulation 

 over the water-shed and sea-basin of the Mediterranean, that they 

 take up there more water as vapor than they deposit. But, throw- 

 ing out of the question what is taken up from the surface of the 

 Mediterranean itself, these winds deposit more water upon the wa- 

 ter-shed whose drainage leads into the sea than they take up from 

 it again. The excess is to be found in the rivers which discharge 

 themselves into the Mediterranean ; but so thirsty are the winds 

 which blow across the bosom of that sea, that they not only take 

 up again all the water that those rivers pour into it, but they are 

 supposed by philosophers to create a demand for an immense cur- 

 rent from the Atlantic to supply the waste. It is estimated that 

 three* times as much water as the Mediterranean receives from 

 its rivers is evaporated from its surface. This may be an over- 

 estimate, but the fact that evaporation from it is in excess of the 

 precipitation, is made obvious by the current which the Atlantic 

 sends into it through the Straits of Gibraltar; and the difference, 

 we may rest assured, whether it be much or little, is carried off to 

 modify climate elsewhere — to refresh with showers and make 

 fruitful some other parts of the earth. 



548. The great inland basin of Asia, which contains the Sea of 

 The winds that give ^^^^ ^^^ ^^^ Caspian, is situated on the route which 

 Ss^have^to^JJS'the ^^^^ hypothcsis rcquircs thcsc thirsty winds from 

 steppes of Asia. southcast tradc-wiud Africa and America to take; 

 and so scant of vapor are these winds when they arrive in this 

 basin, that they have no moisture to leave behind ; just as mucb 

 as they pour down they take up again and carry off. We know 



* Vide article "Physical Geography," Encyclopaedia Britannica. 



