STUDY IV. 237 



elevated iflands are, befides, frequently found at 

 the confluence of a fmaller and a greater river. 

 They ferve to facilitate their communication, and 

 to open a double paflage to the current of the 

 fmaller river. As often then as you fee iflands in the 

 channel of a great river, you may be aflured there 

 is fome lateral inferior river, or rivulet, in the vi- 

 cinity. 



There are, in truth, many of thefe confluent 

 rivulets which have been dried up by the ill-ad- 

 vifed labours of men, but you will always find, 

 oppofite to the iflands which divided their con- 

 fluence, a correfpondent valley, in which you may 

 trace their ancient channel. There are, likewife, 

 fome of thefe iflands in the midfl: of the courfe of 

 rivers, in places expofed to the winds. I fliall ob- 

 ferve, by the way, that we recede very widely from 

 the intentions of Nature, in re-uniting the iflands 

 of a river to the adjoining Continent ; for it's wa- 

 ters, in this cafe, flow in only one fingle channel, 

 and when the winds happen to blow in oppofition 

 to the current, they can efcape neither to the right 

 nor to the left ; they fwell, they overflow, inun- 

 date the plains, carry away the bridges, and occa- 

 (ion mofh of the ravages which, in modern times,, 

 fo frequently endamage our cities. 



We 



