Field Irrigation by Flooding 341 



to cut, a common plow is driven up one side and 

 down the other of the furrow, thus filling it and 

 leaving the field in shape to be driven over with the 

 harvesting machine. The ridge of earth on each side 

 of the distributing furrow serves the purpose of 



Fig. 85. Canvas dam taken up. 



v 



borders to the lands, which prevent the return of 

 the water to the furrows after it has been thrown 

 out by the darn, shown at the point where the man 

 stands in the cut. 



This dam is simply a piece of canvas tacked by 

 one edge to a strip of wood 2x4 inches in thick- 

 ness and 6 or 8 feet long, as seen in Fig. 85. 



