PROFESSOR OLMSTED'S OBJECTIONS. 437 



in this case. If a wave in the ocean, for in st? nee, should 

 be an inch high, it would destroy the equilibrium, and a 

 current of heated air would start upwards from its summit 

 and other heated air, or air highly charged with vapor 

 would rush in towards the base of the ascending column, 

 and the action would be continued and increased. 



The Professor gives one more example where he says my 

 theory fails to explain the phenomenon; that is, " why it 

 does not rain in Egypt." And in this instance he says, " I 

 adduce one hypothesis to explain another, contrary to the 

 admitted laws of inductive philosophy." 



To this I answer, that even if the phenomenon in ques- 

 tion is not yet explained by my theory, yet, if it is not con- 

 trary to my theory, and impossible, if my theory is true, 

 then may the theory still be true. But I do riot concede so 

 much. 1 contend that my theory explains the phenomenon, 

 without an hypothesis. It is not an hypothesis that great 

 rains are constantly falling on the mountains of Abyssinia 

 during the whole time that the wind blows from the Medi- 

 terranean, across Egypt towards those mountains. It is 

 not an hypothesis that the upper current of the atmosphere 

 over Egypt runs in the opposite direction from the moun- 

 tains of Abyssinia towards the north. It is not an hypoth- 

 esis that this upper current contains in it the immense quan- 

 tity of caloric of elasticity given out by the great quantity of 

 vapor condensed there. It is not an hypothesis that this air, 

 if brought down to the surface of the earth in Egypt, would 

 be about 40 warmer than the air at the surface. It is not 

 an hypothesis that cold air will not rise in warm, or in air 

 warmer than itself; therefore, if thousands of upmoving 

 columns of air should ascend every day over Egypt, as I 

 suppose they do, they would not penetrate far into the up- 

 per current of air, because that air would be hotter than 

 themselves. Besides, as these two currents move in differ- 

 ent directions, the upmoving columns would be cut in two, 

 and the lower part carried to the south, and the upper to 



