LOCATING DITCH LINES 



205 



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, straight-edged lumber a triangle is made, as indicated in 

 the sketch. The three pieces, A B, 6 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, a. 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 horizontal, 

 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 be- 

 fore 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. 



Starting with the "Jump Scraper" to close a row of gates. 



To use this instrument for locating the line of the ditch, cal- 

 culate the amount which your line should rise between each two 



