152 IRRIGATION. 



tion to the quantity of water admitted to the field, and 

 it may be that the discharge drain, into which the main 

 drains enter, may need to be six or eight inches in di- 

 ameter. This question, as to the size of tile, will need 

 careful consideration, because if the size is insufficient, 

 the flow will be retarded, with the inevitable result of 

 sediment and choked drains. As a general rule, the main 

 pipes for irrigated meadows should be twice as large as 

 those used for ordinary drains, as the excess of surplus 

 water at times may be yery large. Any system of pipes, 

 that is not equal to the most exacting emergency, will be 

 insufficient, and calculations must be made to meet such 

 an emergency. Before any large expenditure of money 

 or labor is made in laying down drains, which once laid, 

 admit of no remedy except total undoing of the work 

 and relaying the pipes, it would be judicious to consult a 

 capable civil engineer, who could readily make safe cal- 

 culations as to the size of pipe, the position of the drains, 

 and the number required. 



H A P T E E XY 



MANAGEMENT OF IRRIGATED *FIELDS. 



When a field has been successfully irrigated and drained 

 at great expense, it may be seriously injured for want of 

 proper management. To care properly for an irrigated 

 meadow calls for the exercise of tact and skill of no mean 

 character. A few general rules may be laid down for the 

 proper management of irrigated meadows, which will 

 serve to meet the majority of cases, and by modifications 

 of which exceptional cases may be met. The point of 

 chief importance is to avoid pasturing. ~No hoof should 

 be permitted upon a completely irrigated meadow, unless 

 it be, under certain restrictions, those of sheep. Sheep 



