100 TILE DKAINAGE. 



expense to screen it and keep it in proper How, summer and 

 winter, and watch the open ditch into which it flows, than 

 each one of the laterals and sub-mains would require if each 

 had a separate outlet. Indeed, it requires less; for it has 

 such force and volume of discharge that it clears its own 

 way. A map in the next chapter illustrates this more fully. 



CHAPTER X. 

 How to Drain ; Special Problems. 



One problem is, how to handle large amounts of surface- 

 water coming from land that lies higher up along the water- 

 shed or slope. Such a problem presented itself in connection 

 with the thorough drainage of the lield of 36 acres shown in 

 Fig. 27. First, let us explain the handling of the surplus 

 water coming from some 40 acres of land, chiefly pasture and 

 meadow, and not tiled, and lying higher up than the lield 

 itself. 



I had the two ponds, A and B, at the southwest side of the 

 lield (see Fig. 27). Beneath the dam of the larger is a two- 

 inch iron pipe with globe- valve for discharge full size of the 

 pipe. This discharges into a sewer-pipe catch-basin marked 

 E, which connects by a four-inch tile drain, and this in turn 

 discharges down the valley through the middle (six-inch) 

 main (see map). The valve is opened in high water. Also 

 the overflow from both ponds in high water enters the six- 

 inch main through the twenty-inch catch-basin in the catch- 

 pond on the southwest side of the field, and marked C. The 

 catch-basin is of twenty-inch sewer-pipe, and the six-inch 

 main enters it by a reversed " trap '' shown in Fig. 28. 



EXPLANATION OF MAP, FIG. 27. 



The single straight lines are two-inch lateral tile-drains, 

 and the double lines are main drains. Southeast of the 



