54 



AGRICULTURAL ENGINEERING 



number of degrees indicating the angle of the line with the 

 true north or south. Thus, a line in the right-hand quadrant 

 is north and so many degrees east; as, N. 4° 37 . E. A line 

 whose direction lies in the left-hand quadrant is north, and 

 so many degrees west. 



The Transit. It is not the purpose to include here 



instructions in the use of the 

 transit. It is desirable, how- 

 ever, to explain in a brief way 

 the instrument. The transit is 

 a universal surveying instru- 

 ment, and it is arranged for 

 measuring horizontal and verti- 

 cal angles, for determining the 

 bearings by the magnetic needle, 

 for leveling, for measuring dis- 

 tances by means of an attach- 

 ment known as stadia wires, 

 and for determining bearings 

 from the sun when provided 

 with a suitable solar attach- 

 ment, and for many other lines 

 of work. 

 PROBLEMS 



Fig. 40. A surveyor's transit. 



The instructor should here arrange practice work in differential 

 and profile leveling, and surveying with the horizontal circle and com- 

 pass as far as the equipment provided will permit. 



QUESTIONS 



1. What is meant by differential leveling? 



2. What is the purpose of profile leveling? 



3. Describe the process of leveling. 



4. How should level notes be recorded in the field book? 



5. What is meant by a back sight? Height of instrument? 

 Fore sight? 



