Of GUIJ NA. 43 



flooded rivers after a rainy feafon. By and by I lliall explain 

 the true canfe of it. 



On approaching the continent of South America, a change 

 on the face of the Jkj will ftrike the attentive obferver. The 

 clouds become lefs diflincfl from each other, and the intervals 

 between them lefs clear. They are blended into one another as 

 it were, and fuffufed more generally over the atmofphere. 

 They appear to be furcharged with vapour, or to have a ftronger 

 diipoiition to depoiit it. 



There is a particular prevailing appearance of the heavens 

 within the tropics when you are at a diflance from continents 

 or very high iflands, which has fo often ftruck me that I won- 

 der it has not been taken notice of. I call it a tropical Jky^ and 

 thus defcribe it. The clouds in fine weather are in a fingle feries 

 or ftratum, failing away regularly with the trade- wind. They 

 are fmall and diflindly feparated froin each other. The inter- 

 vals or fky above them of a clear azure. Tlie lower furface 

 of the clouds is perfectly horizontal. As the temperature is 

 commonly very equal over the fea, the condenfation takes place 

 every where at an equal height from the furface of the water. 

 In the clouds that are over-head, you cannot indeed perceive 

 this J but it becomes more and more viiible as the eye recedes 

 from the zenith. The lower limb of each diftant cloud appears 

 perfecftly level and well defined, brighter than the fuperincum- 

 bcBt part. At a diflance, nothing is to be feen b\it tliefe limbs 

 clofer and clofer in gradation one behind the other ; and the 

 whole horizon round refembles the roof of a ftage, with an in- 

 finity of half dropt curtains as far as the eye can reach. In 

 two voyages from Europe, I have met with this tropical iky as 

 far north as Cape Finifterre. It came with a fair wind, which 

 continued with us like a regular trade- wind, accompanied with the 

 fame appearance of the clouds, till we made the Weft Indies. In 

 running down the trade-winds, every one has an opportunity of 

 verifying this defcription, and muft be ftruck with the beauties 



F 2 which 



