Hydraulic Earn. 553 



chief difficulty is in arranging to convey the water in such 

 a way that it will not become too warm, even if the pipe 

 is carried 3 or 4 feet under ground where it would be safe 

 against frost in winter. The ground becomes warm 

 enough in summer time to leave the temperature unsatis- 

 factory if the water must be carried any considerable 

 distance. The water may be carried in this way to any 

 distance and any hight but the per cent, of the stream con- 

 veyed decreases with both the hight and the distance. 



