58 IRRIGATION FARMING. 



near the surface. As far as possible keep the grade 

 uniform, as changing the grade tends to cause both 

 cutting and silting. A ditch for irrigation on a farm 

 should always be much larger than the acflual demands 

 require. In Spain their hundreds of years' experience 

 has taught them to make their ditches very large. 

 They could thus irrigate their lands quickly and be 

 done with it. The ditches were far less likely to break 

 and could be easily crossed by wagons or farm imple- 

 ments. During sudden showers they could carry off 

 the drainage water from immediately above them and 

 thus avoid many a washout. 



Laying Out.— The laying out of ditches is the 

 province of the engineer or surveyor, although the 

 more intelligent farmers may do much of their own 

 work and thus save considerable expense. Something 

 of a knowledge of leveling must be had in order to do 

 the work, but sufficient may soon be acquired to per- 

 mit of much home work being done. Every man who 

 has much ditch building to do should have a cheap 

 grade level and target, which should not exceed $25 in 

 cost, while a very good outfit can be bought for $12. 

 The writer has used the Jackson very satisfa<5lorily. 

 This instrument is shown in Fig. 7, while the target 

 or flag is given in Fig. 8. 



If but little work is to be done a carpenter's com- 

 mon spirit-level fastened onto a sixteen-foot strip of 

 board will answer very well. Instru<5lions for running 

 grades are sent with each instrument. The first opera- 

 tion is to begin at the seledled head and take a series 

 of long sight levels down the course of the river to 

 ascertain its approximate fall. These levels should be 



