88 



THE OCEAN, 



during the tliree summer months,* while the amount of rain during 

 the year is about 19 J inches. The result is that the Mediterranean 

 constantly loses three times as much water as it receives by its tribut- 

 aries. It is the ocean then which must fill up the void ; a portion of the 



Fig. 24.— The Straits of Gibraltar. 



current which flows from north to south along the coasts of Portugal 

 and Spain, enters by the Straits of Gibraltar, and spreads far into the 

 Mediterranean in superficial sheets. Nevertheless, if this inland sea 

 did not also send a counter-current to the Atlantic, it would sooner 

 or later be changed into an immense plain of salt. Incessantly 

 losing fresh water by evaporation, and always receiving salt water 

 from the ocean, its liquid mass would become in the end completely 

 saturated, and the crystals of salt would line the marine bed in 



* r.egy, Annules des Fonts et Chaussees, 1863. Vigan, ibid. 1866. 



