The document discusses theodolites, which are surveying instruments used to precisely measure horizontal and vertical angles. Theodolites have three leveling screws and an optical plummet or prism, and can be used to establish straight and curved lines, measure distances, and establish elevations. Modern electronic theodolites have digital readouts and can measure angles more precisely than older optical theodolites. The document also describes how to set up a theodolite and take angle measurements, as well as techniques for prolonging measurement lines past obstacles using triangulation or offsets.

1. CE 260 SURVEYING CHAPTER 5

20. THEODOLITES

21. Angle Measurement with an Optical Theodolite

24. DIRECT OPTICAL THEODOLITE

31. PROLONGING A MEASUREMENT LINE BY TRIANGULATION OVER AN OBSTACLE

33. PROLONGING A LINE PAST AN OBSTACLE