30 BULLETIN 115, U. S. DEPARTMENT OF AGRICULTURE. 



which equals 21.39, or 21§ inches expressed to the nearest sixteenth of 

 an inch. Therefore on the plans as shown the width of opening for 

 the smaller channel would be 2 If inches ; then comes the 2-inch divi- 

 sion board and then the remainder of the 6-foot width of main box, 

 or 48f inches. 



Assuming that the width of the ditch remains about the same and 

 that the next consumer has 8 of the 36 shares of stock, after passing 

 the first box the water represents 36 shares less 11 shares, or 25 shares, 

 and the width of the opening leading to the delivery box becomes 



77) = A ° r X = 22A or 22 i inches. 



Note that all of the posts supporting the division wall are set in the 

 larger channel for the reason that any influence due to these posts 

 would affect the larger channel less in proportion than the smaller one. 

 These posts go through the floor but are not set into the sill as 

 are the outside posts. The check or weir board goes completely across 

 both channels and the lower board of the division wall is cut to set 

 down over the check board. For a large division box on this plan, or 

 where the soil of the channel below the box is eroded easily, a lower 

 cut-off wall and a wing on the side opposite to the delivery box should 

 be added to the structure. 



The siding and floor of this structure are given as 2-inch stuff. In 

 southern California, where densely fibered redwood is obtainable, 

 1-inch stuff would suffice. The thickness of the boards may be altered 

 to suit the local lumber. 



The only piece of hardwood in the structure is the cutwater, which 

 should be of oak or it will not last long. It should be screwed into 

 the ends of the division Avail boards and tightly screwed to the cap 

 and to the sill. This construction saves the use of any side posts 

 above the weir board, which posts would alter the proportionate 

 division of water. Thin strips of sheet iron may be fastened to each 

 side of the division wall with stove bolts to strengthen it. The up- 

 stream side of the cutwater is beveled to a knife edge, as shown, from 

 the floor to the cap. It is to be noted that the width of the division 

 board is deducted from the total width of the main box; that is, 2 

 inches is deducted from 72 inches, leaving 70 inches to be divided 

 proportionally. 



The weir board is placed 3 feet down the channel of the box in 

 order to suppress the contraction and make the flow over the board 

 approximately proportional to the length between walls. This box 

 is designed to be used where there is not sufficient fall to the land 

 to make a clean drop in the ditch at the division box, but this board 

 will reduce the influence of the water below the board so that the 



