in diminishing the Quantity of Water in Rivers. 103 



the return of the rainy season will be much less regular if the 

 face of the country be exposed and arid ; also if cultivation to 

 a great extent has partially taken the place of forests ; and fi- 

 nally, if the rivers are less common and the lakes more scarce. 

 The rains will then be much less abundant, and, in such coun- 

 tries, droughts of long duration will from time to time be 

 experienced. If, on the contrary, thick forests nearly entirely 

 cover the whole territory, if the rivers are numerous, the cul- 

 tivation be but limited, then the irregularity of the seasons will 

 still manifest itself, but with quite a different character. Rain 

 will then predominate, and in some years it will become, so to 

 speak, continual. 



The continent of America presents to us, in immense^ extent, 

 two regions which are placed under the same conditions as to 

 temperature, and in which we successively meet those circum- 

 stances which are the most favourable to the formation of rain, 

 and those which are of directly opposite character. In leaving 

 Panama, and travelling towards the south, we pass the Bay of 

 Cupica, the provinces of San Buena Vantura, of Choco, and of 

 Esmeraldas. In this country, covered with thick forests, and 

 furrowed by a multitude of rivers, the rains are almost unceas- 

 ing. In the interior of Choco no day passes without rain. 

 On the other side of Tumbez, towards Payta, an entirely dif- 

 ferent set of objects present themselves. The forests disap- 

 pear, the soil is sandy, and of vegetation there is scarcely a ves- 

 tige. Here rain, so to speak, is unknown. When I was at 

 Payta, according to the testimony of the inhabitants, it had 

 not rained for seventeen years. This want of rain is common 

 in all the countries which border on the desert of Sechura, and 

 extends as far as Lima. In these countries rain is as seldom 

 seen as are trees. 



Thus, in Choco, whose soil is covered with forests, it rains 

 continually ; on the coast of Peru, the soil of which is sandy, 

 devoid of trees, and destitute of verdure, it never rains ; and 

 this, as I have already said, under a climate precisely the same 

 as to temperature, whose exposure and distance from the nioun- 

 tains is very nearly the same. Piura is not at a greater dis- 

 tance from the Andes of Assuay, than are the humid plains of 

 Choco from the western Cordillera. 



