QUESTIONS 138 



To Demonstrate How Tile Works. — Procedure. — Obtain three 3-inch 

 clay or shale tile and two water-tight wooden boxes about 10 X 12 X 10 inches. 

 Cut two holes in each box in opposite sides near the bottom, large enough to 

 allow the tile to enter. Place one tile in the first box so that the two ends 

 will project from either side. Place the other two tile end to end, with the 

 joint in the middle of the box and the ends of the tile projecting from opposite 

 sides of the box. Make both boxes water-tight by means of paraffin oi p.nint 

 (do not seal the joint between the tile in the box containing the two tile) 

 and fill each box with sandy soil. Saturate the soil in both boxes with water 

 and note results. 



Questions. — (a) How do tile work under field conditions? 



(b) Are there any objections to the use of glazed tile? 



(c) About what per cent of the drainage water passes through the walls 

 of the tile? 



Laboratory Exercises (optional). — Material Needed. — Ditching spade; tile 

 hook; a number of tile; a few laths; a drainage level; and whatever other tools 

 found necessary. 



To Construct a Trench for Drain Tile. — The teacher can determine the 

 method of procedure. 



To Become FamiUar With a Drainage Level.-— ^The teacher should deter- 

 mine the need of such an exercise, and plan sufficient work to meet the needs. 



Field Studies. — Observe wet areas, especially those due to seepage. Note 

 the conditions of the subsoil. 



Observe any system of drainage: open ditches, systems of tile drainage, 

 outlet, results, benefits, etc. 



QUESTIONS 



1. What is meant by land drainage? 



2. Why do crops suffer when water stands too long on a field? 



3. Name other harmful effects of the lack of drainage. 



4. Name and discuss the benefits of thorough drainage. 



5. Give reasons why some lands are wet. 



6. Discuss the need of land drainage in the United States. 



7. How may wet lands be drained? Describe briefly the different methods, 



and conditions under which used. 



8. What is the first step in draining land? How may this information 



be obtained? 



9. What can be done with a spade ia land drainage? 



10. How can plow furrows serve as chains? Illustrate by a diagram or sketch. 



11. What is a surface-run? What is its use and how made? 



12. Explain the uses of open ditches in land drainage. 



13. What are the objections in constructing many small ditches? How can 



these objections be overcome? 



14. What is meant by tile drainage? What are drain tile? 



15. How are tile laid, and how deep? 



16. What is meant by "line of tile"? Gradient? What relation is there 



between gradient and the size of tile to use? 



17. How may the grade line be deterroined in digging the trench for tile? 



Explam by use of diagram the use of grade lath. 



18. What is meant by "blinding" tile? 



19. How far apart should Mnes of tile be laid? 



