RUNNING LINES FOR DITCHES 



183 



A strong current in soft soil may cause mischievous erosions. Water 

 carrying much sediment must never be allowed to move sluggishly, 

 as clear water sometimes may. It is best to state the requirements 

 to a competent engineer and act on hib suggestion, or secure the 

 counsel of a neighbor who has had experience with similar soil and 

 water. 



Having decided what fall to give the ditch, the nearest point of 

 which water can be taken out of the creek to be brought to a certain 

 piece of land is found by commencing with the point at which the 

 water is to be delivered (generally the highest point of the land to 

 be irrigated), and running up stream a line which has the inclination 

 intended for the ditch. 



To stake out this line when no special hindrances are in the way, 

 use a home-made leveling instrument constructed as follows : 



With sound, stranght-edged lumber a triangle is made, as indicated in the 

 sketch. The three pieces, A B, 10 feet long, B C, 12 feet long, and C A, 4 

 feet long, are made fast to each other at A, B, and C. The board, A D is 

 fastened to the triangle at right angles to B C near A on the board, A D, 

 plumb-line is made fast. The plumb, like a mason's plumb, hangs in a hole 

 at F, so that when A D is vertical, the string hangs very near the surface of 

 the board, A D. 



It will be seen that when A D is exactly vertical, B C is exactly hori- 

 zontal, if the angles at D are true right angles. An ordinary carpenter's 

 square used in the construction of the apparatus will insure sufficient accuracy 

 in the position of A D. 



In marking on the board, A D, however, the line in which the string of 

 the plumb will hang when B C is exactly horizontal, more care is required. 

 Two pegs are driven, as far apart as B and C, for these points to rest on. 

 The highest one is driven into the ground until the plumb-line follows about 

 the center line of the board, A D. Having marked this position of the plumb- 

 line, the triangle is reversed so that the end B rests on the peg, where 

 before we had the end C, and vice versa. Should the plumb-line be in a 

 position at variance with the first one marked on the board, then the correct 

 position for the B C horizontal will be exactly in the middle between the two 

 found by the aid of the two pegs. 



It will frequently be found convenient to have a scale of feet marked off 

 on B C. Holes in the pieces A B and C A at E E, or handles, will make the 

 triangle convenient to carry. Only two men are necessary in using it. 



A home-made leveling instrument. 



