124 THE PHYSICAL GEOGRAPHY OF THE SEA. 



mosphere whose functions are manifest, but whose presence has 

 never yet been clearly recognized. 



298. 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. 



