DRAINAGE. 



113 



Fig. 46.— Silt-basin of vitrified 



pipe- 



deposit of silt may be watched and removed, until it ceases to 



accumulate, when the ditch may be permanently filled in. 

 Filling in the Ditches. — As fast as 



the tiles are laid, they should be securely 



covered, in order that they may not be 



broken by stones falling in from the banks, 



and that their position may not be dis- 

 turbed by the water running in the ditch. 

 The best covering to place immediately 



over the tile, is the heaviest and stiffest clay 



from the ditch, because this compacts more 



readily than any other material, and allows 

 less of its finer particles 

 to enter the tile. It is 

 a mistake to suppose 

 that there is the least 



necessity for placing a porous material next 

 to the tile. Especially should sods, or other 

 covering which contain organic matter, be 

 avoided, as affording a less firm packing 

 around the tile, and, on the decay of the or- 

 ganic parts, furnishing loose particles to enter 

 the joints. Throw in fine clay, — dropping it 

 gently about and over the tiles, until they are 

 well covered, and then fill in to a depth of eight- 

 een inches with clay. This filling should now 

 be trampled down with the feet, and then 

 rammed with a wooden maul (Fig. 47) until 

 quite firm. By this process, the tile will be 

 securely clasped by the clay, and the least pos- 

 sible amount of silt will enter the drain. As 

 to the entrance of the water, the young drainer 



Fig. 47.-Maul for ramming. ^^^^ g|^,g ^^^^^\^ ^^ trOublc. To USC the lan- 

 guage of an English farmer, " experience will prove that you 

 can't keep it out, and it is astonishing how soon the water will 

 learn how to get in, even if strong clay is rammed tight over 



