DRAINAGE 



159 



nometry, and even persons with only a knowledge of 

 arithmetic, with a moderate amount of technical instruc- 

 tion, can make use of it to a limited extent. It is an 

 instrument for the use of the engineer, however, rather 

 than for the use of those who are not specialists in the 

 line of surveying. Transits, such as professional en- 

 gineers use, are scientific optical instruments of a high 

 order and are expensive, costing about $200. There are 

 cheaper instruments, and also less expensive combined 

 forms of level and transit for the use of farmers. These 

 cost about $50. The farmer who has been well trained 

 in an agricultural school, or who has otherwise learned 

 the use of surveying instruments, can do his own work 

 in small drainage projects cheaply and well. By means 

 of the transit a permanent record may be made, showing 

 on a plat of the 

 land through 

 which drains 

 pass the exact 

 location of the 

 drainage lines. 

 In most cases 

 such records 

 and plats may 

 be made from 

 measurements 

 without the use 

 of a transit. 



A map or 



drawing of the system should be made, locating section 

 corners of the government survey, where that is prac- 

 ticable. Points or lines from which to measure the 

 various lines of the drains, and their point of junction 

 and their extremities, maybe definitely located in relation 

 to certain natural objects or artificial monuments, as 

 the lines subdividing the section, or monuments mark- 



Figure 59. Leveling instrument on which sights are attached 

 to a common pocket, or better, a mason's spirit level. T, 

 thumbscrew; H, hinge. 



