66 ENGINEERING FOR LAND DRAINAGE 



these two sides as bases from which to work. Have 

 stakes prepared which should be about 1 6 inches long. 

 Common lath are good for this purpose. Begin at the 

 corner and measure off a base, setting a stake at each 

 station of 1 00 feet. Letter the stake at the corner A 

 and the others By C, D, etc., in order. This is the base 

 line. Begin at the point A and measure from that 

 point along the adjacent side of the field, and number 

 these stakes i, 2, 3, etc., until the limit of the field is 

 reached. The last stake should record the length of 

 the line in feet. 



Set a flag 100 feet from the last stake at a right angle 

 with the line run, so that a line can be run parallel with 

 the first. Begin at the stake B on the base line and 

 measure a line and set stakes parallel to the first line. 

 Proceed in the same way across the entire farm until 

 it is entirely checked into squares of 100 feet. In lay- 

 ing off these lines, they should be kept straight by 

 means of flags, which are set ahead of the work, and in 

 case a prominent feature, such as a centre of a pond or 

 a stream is crossed, an intermediate stake should be set 

 and properly numbered. These lines can now be de- 

 scribed as -4, By Ci etc., lines, and any point on that 

 line by the number of the stake on it. 



The next work is to ** book ' ' the farm or field, as the 

 case may be. For convenience it will be best to select 

 the lowest point on the farm as a datum if it is ap- 

 parent to the eye. If not establish a <* bench-mark " 

 and assume a datum plane at the initial point or A of 

 the base line. Take each line in order and take a 

 level at each stake, recording the elevation of the sur- 

 face under its proper head. The headings of the level 



