§ 332. RED FOGS AND SEA BREEZES. 147 



labels on the wind, to "tell whence it cometh and whither it go- 

 eth," yet there evidently is an agent concerned in the circulation 

 of the atmosphere whose functions are manifest, but whose pres- 

 ence has never yet been clearly recognized. When the air which 

 the northeast trade-winds bring down meets in the equatorial calms 

 that which the southeast trade-winds convey, and the two rise up 

 together, what is it that makes them cross? where is the power 

 that guides that from the north over to the south, and that from 

 the south up to the north? The conjectures in the next chapter 

 as to "the relation between magnetism and the circulation of the 

 atmosphere" may perhaps throw some light upon the answer to 

 this question. 



