DRAINAGE, 



105 



Fig. 33. 



Fig. ji. — Bracing the sides 

 in soft lands. 



100 feet is recommended whenever it can be easily obtained — not 

 especially as being more efFective, but as requiring less precision 

 and expense. 



Digging the Ditches. — It is not necessary that a ditch for 

 tile-draining should be more than four inches wide at the bottom, — 

 only wide enough to allow the workman to 

 stand with one foot in front of the other, — and 

 if it widens to twenty inches at a height of four 

 feet from the bottom, he will have room enough 

 to work in. Soils which are tolerably retentive 



will stand at this angle during 



the short time that ditches need 



remain open. If inclined to 



cave in, the weaker places may 



be supported by boards braced 



against the opposite side. (Fig. 



For four-foot drains, stretch two lines, parallel 

 to each other, twenty inches apart, leaving the 

 stakes at a distance of two or three inches from 

 one side of the inclosed space. Then, with an 

 ordinary spade, cut the lines neatly, remove the 

 surface soil, and throw it on the staked side of the 

 line. Dig the ditch to a depth of three feet, 

 throwing the lower soil on the bank opposite to 

 that on which the surface soil has been placed. 

 Now, take a narrow ditching spade. Fig. 33, four 

 inches wide at the point, and dig down opposite 

 the stakes to the depth marked thereon. The 

 depth may be measured by an instrument simi- 

 lar to that represented in Fig. 34. Having reached 

 this point, set up at each of two or more of the 

 stakes a " boning-rod," seven feet long. Fig. 35, 

 fastening it In place by laying two bits of board 

 ^"'^- across the drain, holding the boning-rod between 



and held in place by stones or earth laid on their ends. 



W 



Fig. 54 — Measuring 



them. 



