282 PHILOSOPHY OF STORMS. 



he clearly shows that not one of the causes which others 

 have assigned can account for the phenomenon. 



If the cause, however, which he assigns, is the true one, 

 it was unnecessary to mention mine, for the establishment 

 of one is the refutation of the other. 



But the professor also thinks that " part of the depression 

 is due to the upward motion of the air." 



To this proposition I cannot assent. 



Let the reader imagine one barometer in the inside of a 

 storm cloud near the top, ten miles from the surface of the 

 earth, and another at the same elevation on the outside of 

 the cloud. Now though there is a strong current of air 

 rushing upwards, past the barometer in the cloud, yet that 

 barometer will stand higher than the one on the outside 

 which is in no such under current. (175.) 



The reason it will stand higher is that there is more air 

 over the one in the top of the cloud, than over the other on 

 account of the expansion of the air in the cloud, and its 

 swelling up to the very top of the atmosphere and rising 

 higher there than in surrounding regions. Indeed the very 

 fact, that the air spreads outwards on all sides in these high 

 elevations from the centre of the storm, which professor 

 Loomis admits, and indeed proves, is itself an absolute proof 

 that the barometer stands higher at the place from which 

 the air spreads out, than it does at the places towards which 

 the air moves on the same horizontal level. 



In the torrid zone at the surface of the earth, the barome- 

 ter stands lower than it does at the arctic circle, yet no one 

 who thinks will doubt that at ten or fifteen miles above the 

 earth's surface, the barometer would stand higher in the 

 warm latitude than in the cold, because it is farther to the 

 top of the atmosphere where the air is more expanded by heat. 



The following chart and table of barometric fluctuations, 

 are so highly important, that I copy them entire, with the 



