198 THE PHYSICAL GEOGRAPHY OF THE SEA. 



we may now fancy that, in this exquisite system of adaptations 

 and compensations, we can almost behold, in the Red and Medi- 

 terranean Seas, the very waters that were held in the hollow of 

 the Almighty hand when he weighed the Andes and balanced the 

 hills of Africa in his comprehensive scales, 



415. In that great inland basin of Asia which holds the Caspian 

 Sea, and embraces an area of one million and a half of geo- 

 graphical square miles, we see the water-surface so exquisitely 

 adjusted that it is just sufficient, and no more, to return to the at- 

 mosphere as vapor exactly as much moisture as the atmosphere 

 lends in rain to the rivers of that basin. 



416. Thus we are entitled to regard (§ 390) the Mediterranean,, 

 the Red Sea, and Persian Gulf as relays, distributed along the 

 route of these thirsty winds from the continents of the other hemi- 

 sphere, to supply them with vapors, or to restore to them that which 

 they have left behind to feed the sources of the Amazon, the Ni« 

 ger, and the Congo. 



The hypothesis that the winds from South Africa and America 

 do take the course through Europe and Asia which I have mark- 

 ed out for them (Plate VII.), is supported by so many coincidence, 

 to say the least, that we are entitled to regard it as probably cor- 

 rect, until a train of coincidences as striking can be adduced to 

 show that such is not the case. 



417. Returning once more to a consideration of the geological 

 agency of the winds in accounting for the depression of the Dead 

 Sea, we now see the fact most strikingly brought out before us, 

 that if the Straits of Gibraltar were to be barred up, so that no 

 water could pass through them, we should have a great depression 

 of water-level in the Mediterranean. Three times as much water 

 is evaporated from that sea as is returned to it through the rivers. 

 A portion of water evaporated from it is probably rained down and 

 returned to it through the rivers ; but, supposing it to be barred 

 up, as the demand upon it for vapor would exceed the supply by 

 rains and rivers, it would commence to dry up. As it sinks down, 

 the area exposed for evaporation would decrease, and the supplies 

 to the rivers would diminish, until finally there would be estab- 

 lished between the evaporation and precipitation an equilibrium, 

 as in the Dead and Caspian Seas ; but, for aught we know, the 

 water-level of the Mediterranean might, before this equilibrium 



