THE MEDITERKANEAN SEA. 257 



of salt at the bottom of the sea. No such deposits have 

 been found in sounding; but the observations of Wollaston 

 upon specimens of water obtained from different depths, 

 show a specific gravity greatly augmented at the deeper 

 levels ; instanced especially in one case, where water from a 

 depth of 670 fathoms about fifty miles within the Straits, 

 was found to contain four times the usual quantity of salt ; and 

 to have a specific gravity equivalent to this large excess. This 

 is so singular a result as to have created doubt respecting its 

 accuracy. Dr. Wollaston's inference from it that there must 

 be a dense lower current running out of the Mediterranean, 

 and carrying into the Atlantic the surplus salt of this inland 

 sea, can hardly be maintained in face of the fact already 

 mentioned of a bar traversing the Straits, with a maximum 

 depth at this place of 150 fathoms. No stream of denser 

 water, coming from greater depths, could rise upwards so as 

 to surmount this impediment. The question altogether must 

 be left to future and more multiplied observations. 



The physical history of the Mediterranean cannot be com- 

 plete . without some notice of the winds, which move this 

 great mass of inland waters. We do not find here, nor could 

 we expect their existence, the constant or strictly periodical 

 atmospheric currents which sweep over the wider oceans of 

 the globe. In a landlocked basin thus irregular in outline, 

 studded with mountain-isles and girt round in great part by 

 mountain chains, local causes modify or predominate over 

 those general conditions to which the atmosphere is subjected 

 by the rotation of the earth, and its annual revolution round 

 the Sun. To other influences on the winds of this Sea must 

 be added that of the vast African desert, stretching for 2,000 

 miles in a direction parallel to its southern shore, and in 

 parts touching upon it ; an enormous waste of bare sand 

 or rock, vehemently reflecting the rays of a southern sun, 

 and acting as a furnace on the atmosphere above it. In 



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