EED FOGS AND SEA BEEEZES. 135 



come cool and fresh from the pure snows of the Ancles. Betvreen 

 this range and the coast, instead of marshes and a jungle, there is 

 a desert — a rainless country, upon which the rays of the sun play 

 with sufficient force not only to counteract the trade-wind power and 

 produce a calm, but to tm^n the scale, and draw the air back from 

 the sea, and so cause the sea breeze to blow regularly. 



318. On the coast of Africa, on the contrary, a rank vegetable 

 Influences which re- gTOwth scrcons the soil from the scorching rays of 

 giiiate then- strength. ^j^Q ^^j^^ ^j^^ ^--^q rarcfaction iS uot ovcry day 

 sufficient to do more than counteract the trade-wind force and 

 produce a calm. The same intensity of ray, however, playing upon 

 the intertropical vegetation of a lee-shore, is so much force added to 

 the sea breeze ; and hence, in Brazil, the sea breeze is fi'esh, and 

 strong, and healthful ; the land breeze feeble, and therefore not so 

 sickly. Thus we perceive that the strength as well as regularity 

 of the land and sea breezes not only depend upon the topography 

 of a place, but also upon its situation with regard to the prevail- 

 ing winds ; and also that a given difference of temperatui'e 

 between land and water, though it may be sufficient to produce 

 the phenomena of land and sea breezes at one place, v\'ill not be 

 adequate to the same effect at another ; and the reason is perfectly 

 philosophical. 



319. It is easier to obstruct and turn back the current in a 

 Lnna breezes from sluggish tliau iu a rapid stream. So, also, in 

 AWca scorching hot. tiu^ning a currcut of air first upon the land, then 

 upon the sea — very shght alternations of temperatm^e would suffice 

 for this on those coasts where calms would prevail were it not for 

 the land and sea breezes, as, for instance, in and about the region 

 of equatorial calms ; there the air is in a state of rest, and will 

 obey the slightest call in any direction ; not so in regions where 

 the trades blow over the land, and are strong. It requires, under 

 such circumstances, a considerable degree of rarefaction to check 

 them and produce a calm, and a still farther rarefaction to turn 

 them back, and convert them into a regular sea breeze. Hence the 

 scorching land breeze (§ 317) on the west coast of Africa : the 

 heat there may not have been intense enough to produce the 

 degree of rarefaction required to check and turn back the south-east 

 trades. In that part of the world, their natural course is from 

 the land to the sea, and therefore, if this view be correct, the sea 

 breeze should be more feeble than the land breeze, neither should it 

 last so long. 



