94 AGRICULTURAL ENGINEERING 



In laying through quicksand, time should be given for 

 the water to drain out and allow the sand to become as firm 

 as possible. This is rather a slow process at times, but it is 

 the only method to follow in watery quicksand. To prevent 

 the sand from flowing into the open end of the tile, a screen 

 of hay or grass may be used. If there are bad pockets, it 

 may be necessary to lay the tile upon boards to keep them 

 to grade. 



Inspection. Before the tile are covered the work should 

 be thoroughly inspected to see that the tile are laid to grade, 

 and that the openings between the tile are not too large. In 

 inspecting the grade, the level may be set over the line of tile 

 and the line of sight set to the same slope as the grade line. 

 The reading of the rod held upon the top of the tile should be 

 the same at all points, so long as the slope of the grade line 

 does not change. After inspection, the tile should be 

 " blinded in" by cutting enough dirt from the side of the 

 ditch to cover it to the depth of two or three inches. This 

 earth from the side of the ditch is more porous than that from 

 the surface, and permits the water to enter the tile more 

 readily. The shoveling and spading of the soil have a ten- 

 dency to puddle it and make it water-tight. After blinding, 

 the ditch may be filled. 



QUESTIONS 



1. What is the work of the tiler? 



2. Explain in a general way the digging of tile ditches by hand. 



3. Name and describe the tools used in tile ditching. 



4. Where may tile ditching machines be used to advantage? 



5. How much ditch may be dug with a machine in an hour under 

 favorable conditions? 



6. Why should not tile be laid by guess? 



7. Explain the "water level" method of installing drains. 



8. Describe the line method of digging ditches to grade. 



