126 IRRIGATION FARMING. 



ber preferable to unseasoned stuff. It is best to tar 

 or creosote well-seasoned lumber, and painting or 

 tarring green material is to be discouraged, as it only 

 induces decay and brings on disappointing results. 

 Tarring may be done in vats before construc5lion, or it 

 may be done afterward by using mops or brushes. 

 We would advise in the latter case the application of 

 boiling hot tar on the inside only and after all joints, 

 seams and crevices had been carefully caulked with 

 oakum. The boxing of flumes is generally of three 

 different forms. In the first the floor is built dire(5lly 

 on stringers and the planking floor placed at right 

 angles with the longitudinal axis of the flume or the 

 flow of the water. The second style is to lay floor 

 beams on the stringers, bracing them at intervals so as 

 to bear the water pressure. The standards and floor 

 beams are boxed in and bolted to the outside braces, 

 the whole forming the foundation for the sheathing or 

 boxing. The third, form, employed more generally on 

 large flumes, consists in framing the floor beams and 

 stringers in cross yokes to receive the boxing. 



A very good representation of a flume provided 

 with a waste-gate is portrayed in Fig. 29. It is cus- 

 tomary to place a waste-gate in each flume, because 

 the strucfture furnishes a cheap mode of introducing an 

 escape, and furthermore it is desirable to be able to 

 empty the canal immediately in case the strudlure 

 should need repair. Where flumes are built on trestles 

 the latter are usually supported on piles, though in 

 cases where the bed of the drainage is of sufficiently 

 firm nature, they. rest simply on mudsills. Suitable 

 drains and wings must be provided at both ends of the 



