1848.] CAUSES OV THE EVAPORATION. 503 



depth, width, and velocity of its more constant tributaries, I 

 had estimated the quantity of water which the Dead Sea 

 was hourly receiving from them at the time of our visit, but 

 tlu calculation is one so liable to error, that I withhold it. It 

 is scarcely necessary to say, that the quantity varies with 

 the season, being greater during the winter rains, and much 

 less in the heat of summer.' ; * 



After the notion in regard to a subterraneous outlet began 

 to be questioned, and the process of evaporation constantly 

 going on came to be better understood, it was said that the 

 rapidity of the latter was occasioned by the volcanic fires at 

 the bottom of the sea. Scientific, as well as uneducated 

 men, seemed determined to make what was peculiar still 

 more strange and singular, and to explain everything, if the 

 expression may be used, in as difficult a manner as possible. 

 A simple fact, easy to be ascertained, puts an end at once to 

 the theory of subterraneous fires. At the surface of the sea 

 the water is from twenty to thirty degrees warmer than 

 below, and at the bottom it varies but little from 50 deg. 

 No doubt, the evaporation is very rapid ; but we must re- 

 member that the sea is confined between two lofty walls of 

 mountains, in a narrow chasm, and that during the greater 

 part of the year, the burning rays of a tropical sun are poured 

 directly upon it. No gentle breezes fan its waters and cool 

 the air ; but the hot simoom of the Arabian Desert that 

 whistles through the dark gorges of Wady-el-Arabah, and 

 disturbs its usually silent waters, produces the same effect 

 with the intense heat. 



Some idea may be formed with regard to the rapidity of 

 the evaporation, from the fact that the atmosphere, within a 

 wide circuit around the lake, is impregnated with the sub- 

 stances contained in its waters. The fetid smell noticed by 

 every traveller was once supposed to be a property peculiar 

 to the sea itself; but this is now admitted to be produced by 

 the hot sulphurous springs on its margin. Everything metal- 



* Narrative, p. 377. 



