158 PHYSICAL GEOGBAPHY OF THE SEA, AKD ITS METEOROLOGY. 



l\ow obseryations have shown that the winds represented by T IT 

 are rain vands ; those represented by D E, diy winds ; and it is 

 evident that ABC could not bring any vapours to these calms to 

 serve for T U to make rains of; for the winds represented by 

 ABC have already performed the circuit of surface winds as 

 far as the pole, during which jomiiey they parted with all their 

 moistm^e, and, retrnming through the upper regions of the air to the 

 calm belt of Cancer, they arrived there as diy winds. The winds 

 represented by D E are dry winds ; therefore it was supposed 

 that these are, for the most part, but a continuation of the winds 

 ABC. On the other hand, if the winds ABC, after descending, 

 do tiuii about and become the surface winds T U, they would first 

 have to remain a long time in contact with the sea, in order to be 

 supplied with vapom- enough to feed the great rivers, and supply 

 the rains for the whole earth between us and the north pole. In 

 this case, we should have an evaporating region at sea and a 

 rainless region ashore on the north as well as on the south side 

 of this zone of Cancer ; but investigation shows no such region. 

 Hence it w^as inferred that B C and E S do come out on the 

 smface as represented by Plate I. But what is the agent that 

 should lead them out by such opposite paths ? According to this 

 mode of reasoning, the vapom-s which supply the rains for T U 

 would be taken up in the south-east trade-wind region by Q, 

 and conveyed thence along the route Q E S to T. And if this 

 mode of reasoning be admitted as plausible — if it be true that 

 E S carry the vapom* vfhich, by condensation, is to water with show- 

 ers the extra-tropical regions of the northern hemisphere, Nature, 

 we may be sm^e, has provided a guide for conducting S T across 

 this belt of calms, and for sending it on in the right way. Here 

 it was, then, at this crossing of the winds, that I thought I fii'st 

 saw the footprints of an agent whose character I could not com- 

 prehend. Can it be the magnetism that resides in the oxygen of 

 the air ? Heat and cold, the early and the latter rain, clouds and 

 sunshine, are not, we may rely upon it, distributed over the earth 

 by chance ; they are distributed in obedience to laws that are as 

 certain and as sure in their operations as the seasons in their 

 rounds. If it depended upon chance whether the dry an- should 

 come out on this side or on that of this calm belt, or whether the 

 moist air should retmn or not whence it came — if such were the 

 case in nature, we perceive that, so far from any regularity as to 

 seasons, we should have, or might have, years of drought the most 



