296 



ENGINEERING ON THE FARM 



outlet. Moving water does not injure field crops, and if 

 standing water is removed inside of twenty-four hours, 

 there is no harm done. In northern latitudes it is necessary 

 to have the tile outlet so located that it will be free from 

 water at the freezing period. 



It is essential that where a tile drain outlets into an open 

 ditch the outlet end be protected in some manner. As the 

 tile are only a foot in length, the end joint is easily washed 

 out, or may be destroyed by scaling when exposed to air 



After University of Minnesota 



Fig. 244. Difference in inside area caused by different methods of nailing 

 together 2" x 6" plank for tile outlet projection 



and frost. As soon as the end pipe is destroyed the next one 

 above is subject to the same destructive influences, thus 

 interfering with the outlet and often preventing the proper 

 discharge and causing sediment to settle. A protective 

 structure for a tile laid into an open ditch is commonly spoken 

 of as a tile outlet. 



The practice in the past has been to make this outlet of 

 wood, protecting the opening with a wire screen to prevent 

 the entrance of animals. The use of the screen is being dis- 

 continued in many localities, and the wooden boxes are being 

 replaced by pipe made of very hard burned clay, metal, or 

 concrete. Where a screen is used it offers some obstruction 

 to the flow of water, and the end of the pipe should be at 

 least 1 inch larger than the drain before the screen is 

 reached. Pipes or boxes should be carefully tamped in and 



