214 CANAL. 



of this climate, and from the insular situation of 

 the latter countrj'. 



In applying these facts to the canal, I do not 

 2ee that there is any reason to apprehend a scar- 

 city of water, either from the quantity of evapo- 

 ration or the failure of rain. Whatever is taken 

 up by the one, will be returned with increase by 

 the other. And the vicinity of the great lakes 

 will furnish a never failing and plentiful reservoir 

 for all the purposes of evaporation, which will 

 either be returned to the earth in dew or in rain. 

 But difficulties may occur, when the drain and 

 the supply are not contemporaneous. The great- 

 est evaporation takes place during the prevalence 

 of the greatest heat, and the greatest floods of 

 rain occur in spring and autumn. But consider- 

 ing the numerous streams and lakes which can 

 be pressed into the service of the canal, there is 

 no danger but that their wonted supply will 

 more than transcend the deficiencies of temporary 

 droughts and dearths. It is however well known 

 that cultivation has a great influence on the 

 waters of a country — by precluding evaporation 

 from trees, and by creating eight times more 

 evaporation than existed before opening way for 

 the action of the sun. Besides, the loosening of 

 the earth has a tendency to choke up and absorb 

 fhe streams 



