EXPERIMENT STATION BULLETINS. 485 



These stakes assist in the subsequent locating of the grade stakes and 

 sometimes have recorded upon them data concerning the ditch as it is to 

 be dug at their respective grade stakes, 



LATERALS. 



If the drain thus located should be the main drain of a system, the 

 several laterals will be located in the same manner as the main was 

 located, excepting that instead of starting from the outlet of the system 

 each is begun at the proper point along the main. 



If a system like that illustrated in Fig. 2 or in Fig. 3 is to be used no 

 two laterals from opposite sides should be connected with the main 

 at the same point and it is most common to place the laterals as shown 

 in the figure, the laterals from one side connecting with the main mid- 

 way between the points of connection of the laterals of the opposite 

 side. I I ' ! 



If the laterals are to be placed one hundred feet apart then the op- 

 posite laterals will connect at alternate stakes, when these stakes are 

 set 50 feet apart. If the laterals are placed more than one hundred 

 feet apart or less than one hundred feet apart it would simplify mat- 

 ters to drive the stakes locating the main at intervals other than fifty 

 feet. If laterals were to be sixty feet apart then the stakes on the main 

 should be driven thirty feet apart. If the laterals were to be eighty feet 

 apart the stakes on the main should be driven forty feet apart. If the 

 laterals were to be located one hundred twenty feet apart then the 

 stakes on the main should be driven sixty feet apart, and so on. 



THE ANGLES OF THE LATERALS. 



It is common in systems like that illustrated in Fig. 2 to locate the 

 laterals so that their upper angle to the main shall be less than 90 

 degrees. If, however, it should be deemed advisable to run the laterals 

 at right angles to the main as shown in Fig. 3, then they should be 

 turned slightly so as to enter the main at an angle of less than 90 de- 

 grees, the reason being that if the water from the lateral be discharged 

 into a main at an angle of 90 degrees it is likely to interfere with the 

 movement of the water in the main and also to interfere with the ready 

 movement of the silt which may be carried by the waters of the main. 



THE LOCATION OP THE UPPER END OF MAINS AND LATERALS. 



It is not necessary to carry the end of either main or lateral to the 

 very edge of the area to be drained. The water in the soil will move as 

 far and as readily toward the end of the drain as it will laterally toward 

 any other point of the drain. The line of equal influence of the drain 

 at its end is the arc of a circle whose center is the end of the drain. 



HAULING AND DISTRIBUTING THE TILE, 



By this time, the kind, size and amount of tile required for the work 

 will have been determined and purchased. The tile should now be hauled 

 upon the field and distributed close to where the ditches are to be dug. 

 The hauling and distributing should be done before the leveling is done, 



