38 



THE MOISTURE SUPPLY 



attached to the water supply pipe in such a way that it can be 

 readily turned upon its longitudinal axis. A series of small holes 

 are drilled in the pipe at intervals of three to four feet, and small 

 nozzles inserted in the holes. The nozzle and the machine for 

 drilling the holes are covered by letters patent. Care is exercised 

 in drilling the holes to have them exactly in line with one another. 

 When the apparatus is connected up and the water turned on, 

 a fine stream that breaks into a spray issues from each nozzle. 

 By turning the pipe slightly from time to time, the direction of 



Fig. 19. — Field of cabbage furrowed out ready for irrigating. Greclcx , < 



the spray is changed so that eventually the entire area along both 

 sides of the pipe within range of the nozzles is thoroughly watered. 

 By having a series of lines of pipe close enough together so that 

 the spray from one will reach half-way to the next, it is possible 

 to water an area of almost any size. 



IRRIGATION 



Arrangements for watering such as those already described are 

 used principally in humid regions for supplementing the natural 

 rainfall where some special crop is likely to suffer from lack of 



