44 NJTURJL HISTORT 



which this fky prefents at the fetting of the fun. The inhabi- 

 tants of the lower illands may alfo be well acquainted with it. 

 In the higher ones, the attradlion of the mountains ever forms 

 fets of clouds of other appearances, as being produced by other 

 caufes. With our prefent knowledge of meteorology, hardly 

 any other caufe can be affigned for the phenomena above men- 

 tioned, than the conflant equal temperature that every where 

 prevails on the intertropical feas. One analogous fadl however 

 may be mentioned ; the exceedingly fmall range of the baro- 

 meter in the torrid zone. Does the fame caufe regulate fo ex- 

 actly the height of the clouds, and maintain the uniform fu- 

 fpenfion of the mercury ? We might almoft fufpedl it did, were 

 it not well known, that the barometer varies as little upon con- 

 tinents, and in the vicinity of mountains, in thefe regions as 

 elfewhere, tliough the condenfation of vapours is in fuch cafes 

 much more irregular. Upon the continent you will frequently 

 obferve this tropical fky alfo, efpecially in fine fettled weather ; 

 but much more commonly you will find the fky there, and even 

 before you make the coaft, covered with heavy large dark clouds 

 in fome places, and in others, at a greater height, the ferene 

 dappled fky, fo often feen in Europe. 



Winds. — The trade-wind generally prevails all the day long, 

 and on the fea-coaft feldom fails even at night ; but in lefs than 

 fifty miles up the river it is a dead calm at night, and the 

 breeze is not able to penetrate fo far till towards noon. Still 

 farther up we had whole days of a ftark calm, and the heat 

 very intenfe. 



Dews, fogs and temperature. — The dews, following the law 

 which they generally obferve, are very heavy when and wherever 

 there is but little wind, and the hotter the day and evening, they 

 fall the more copioufly ; they were of courfe more abundant up 

 the river than near the fea-coaft. The exhalations in the day-time 



from 



