1. Surveying Instrument Basics ©2004 Dr. B. C. Paul

2. Getting Over Your Point Implied in saying you know one point is the idea that you can set up over the top of it. Exact Point of instrument set up is determined with a plumb bob –Common to have a stake in the ground with a nail in the stake –Instruments have a place to hang a plumb bob down till almost touches the point Need to set up above the point

3. Setting Up Above A Point Tricks –Have to set legs up level and have plumb bob hang down above the point Reality Adjustments –After getting “in the ball park” still have to get things level Leveling will normally move you off the point. –Most instruments allow the head to shift Tightness of leveling knobs free the head to shift or hold it in place

4. Variations on a Theme Theodolites may have “optical plumb bob”, little view finder and scope that allows you to look at exactly what is under you. –Large objects have enough attraction to shift a plumb bob Drove the early British Surveyors nuts when they went to India and the Himalayan Mountains pulled the plumb bobs to the side. Suggested the point was under the instrument –Underground if put the point on the ground some equipment operator is guaranteed to take it out –Put the points on the roof and instrument under the point

5. The Telescope Scope is equipped with cross hairs Telescope Sunshade Eye Piece Focus Eye Piece generally turns clockwise And counter clockwise to focus The cross hairs for your eye Focus knob generally focuses the scope On the field of view

6. Proficiency Time Again Go Out and Set Up Over a Point with a Plumb Bob –Level the instrument –Sight something with the telescope and focus both the object and cross hairs Go Set Up Over a Point with an Optical Plumb Bob –Level and Sight