102 



TILE DRAIN A(i K 



three large diagonal mains, the laterals are 33 feet apart, 

 northwest of these mains they are 49i feet apart. The for- 

 mer were laid eleven years ago, and drained the land so rap- 

 idly and thoroughly that, last fall and winter, when I drained 

 the northwest part of the field I decided to put them 49i 

 feet (three rods) apart. Thus far they seem to be sufficient. 

 The rule of running the laterals straight down the slope 

 would make them cross all contour lines (the dotted curved 



Fig. 28. Sewer-pipe catch-basin, trap, 6-inch tiles, and section of dam 

 (D) of catch-water pond (shown at C, Fig. 27). When the water overflows 

 the two large ponds it rises in the catch-water pond until it overflows 

 the sewer-pipe at A, and passes off through the trap T, and through the 

 6 inch main B C, and finally out at the 10-inch outlet O, near the north- 

 east corner of the map, Fig. 27. 



lines of equal elevation) <(t right angles. It will be seen that 

 they do so as nearly as is possible if we are to have a paral- 

 lel system, which is quite desirable, saving trouble and ex- 

 pense. Near the northeast side of the field a number of the 

 laterals deflect and run due north several rods so as to avoid 

 quite a knoll shown on the map. To run them straight 

 northwest through this would have required deep and expen- 

 sive digging. 



A careful study of the " contour lines" and darts will 

 show just what course is taken in the tiles by all the surplus 

 water that falls on the entire field, and why the mains and 



