112 HORTICULTURE, FORESTRY, FLORICULTURE 



distances vary with the grade of the ditch, but 150 feet is not far 

 from being an average spacing. In temporary ditches the canvas 

 dam is perhaps the best check, but in permanent ditches it pays to 

 use wood or concrete. In this the opening is controlled by a flash- 

 board which may be adjusted so as to hold the water at any desired 

 height and at the same time permit the surplus to flow over the top 

 to feed the next lower set of furrows. 



Head Flumes. Formerly head flumes for orchards were built 

 of wood, but the steady increase in the price of lumber and the de- 

 crease in the price of Portland cement have induced many fruit 

 growers to use cement instead. When built of wood, the length of 

 the sections varies from 12 to 20 feet, 16 feet being the most com- 

 mon. The bottom width runs from 6 to 12 inches, while the depth 

 is usually 1 to 2 inches less. Redwood lumber l 1 /^ inches thick is 

 perhaps the best for the bottom and sides, and joists of 2 by 4 inch 

 pine or fir are commonly used for yokes which are spaced 4 feet 

 centers. Midway between the yokes auger holes are bored and the 

 flow through these openings is controlled. A 2-inch fall for each 

 hundred feet may be regarded as a suitable grade for head flumes, 

 but it often happens that the slope of the land is much greater than 

 this, in which case low checks are placed in the bottom of the flume 

 at each opening. 



A head flume composed of cement, sand, and gravel costs as a 

 rule about twice as much as a wooden flume of the same capacity, 

 but the early decay of wood, especially if it comes in contact with 

 earth, makes the cement flume cheaper in the end. By means of a 

 specially designed machine, which is patented, cement mortar com- 

 posed of one part cement to about six parts of coarse sand is fed into 

 a hopper and forced by lever pressure into a set of guide plates of 

 the form of the flume. Such flumes are made in place in one con- 

 tinuous line across the upper margin of the orchard tract. After the 

 flume is built and before the mortar has become hard, small tubes 

 from % to l 1 /^ inches in diameter, the size depending somewhat on 

 the size of the flume, are inserted in the side next the orchard. The 

 flow through these tubes is regulated by zinc slides. Flumes of this 

 kind are made in five sizes, the smallest being 6 inches on the bot- 

 tom in the clear and the largest 14 inches. 



At a slightly greater cost a stronger flume can be built by the 

 use of molds. The increased strength is derived from a change in 

 the mixture. In the machine-made flume the mixture of one part 

 cement to five or six parts of sand is lacking in strength, for the rea- 

 son that there is not enough cement to fill all the open spaces in the 

 sand. In using molds medium-sized gravel can be added to the sand 

 and the mixture resembles that of the common rich concrete. Such 

 flumes can be built of almost any size from a bottom width of 10 

 inches to one of 40 inches and from a depth of 8 inches to one of 24 

 inches, but when the section is increased beyond about 240 square 

 inches it pays better to slope the sides outward and adopt the form 

 of the cement-lined ditch. The quantity of concrete required per 



