THE GEOLOGICAL AGENCY OF THE AVINDS. 289 



tropic of Cancer ; the lower half is to the south of it ; that the 

 latter is ^dthin the north-east trade-A\iQd region ; the former, in the 

 region where the south-west passage winds are the prevailing 

 winds. The Kiver Tigris is probably evaporated from the upper 

 half of this sea by these winds ; while the north-east trade-^vinds 

 take up from the lower half those vapours which feed the Nile with 

 rain, and which the clouds deliver to the cold demands of the 

 Mountains of the Moon. Thus there are two " wind-roads " cross- 

 ing this sea : to the windward of it, each road runs through a 

 rainless region ; to the leeward there is, in each case, a river rained 

 down. The Persian Gulf hes, for the most part, in the track of 

 the south-west -winds ; to the windward of the Persian Gulf is a 

 desert ; to the leeward, the Eiver Indus. Tliis is the route by 

 which theory would require the vapom- from the Eed Sea and 

 Persian Gulf to be conveyed, and this is the direction in which 

 we find indications that it is conveyed. For to leeward do we find, 

 in each case, a river, telling to us, by signs not to be mistaken, that 

 it receives more water from the clouds than it gives back to the winds. 

 552. Is it not a curious circumstance, that the winds which 

 Certain sea^^nd travcl the road suggcstcd from the southern hemi- 

 counterpoises in the sphcrc should, whcu they touch the earth on the 

 Snery!''^ ™'^" polar sido of thc tropic of Cancer, be so thirsty, 

 more thirsty, much more, than those which travel on either side 

 of their path, and which are supposed to have come from southern 

 seas, not from southern lands ? The Mediterranean has to give 

 those winds three times as much vapour as it receives from them 

 (§ 547) ; the Eed Sea gives them as much as they can take, and 

 receives nothing back in return but a httle dew (§ 376) ; the Per- 

 sian Gulf also gives more than it receives. What becomes of the 

 rest ? Doubtless it is given to the winds, that they may bear it off 

 to distant regions, and make lands fruitful, that but for these sources 

 of supply would be almost rainless, if not entirely arid, waste, and 

 barren. These seas and arms of the ocean now present them- 

 selves to the mind as counterpoises in the great hygrometrical 

 machinery of our planet. — As sheets of water placed where they 

 are to balance the land in the trade-wind region of South Ame- 

 rica and South Africa, they now present themselves. When the 

 foundations of the earth were laid, the Great Architect " measured 

 the waters in the hollow of his hand, and meted out the heavens 

 mth a span, and comprehended the dust of the earth in a measure, 

 and weighed the mountains in scales, and the hills in a balance ;" 



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