A theodolite is a measuring instrument invented in the late 18th century. It was used as an early surveying tool, and was extremely acurate. Thomas Jefferson used such an instrument during his time as a surveyor. Later versions are also known as "Dumpy Theodolite", while 20th century versions use extremely fine optics, or lasers. The tool in it's present,modern versions is indespensible as a surveying/mapping tool.
Process of Measuring Horizontal Angles Using a Theodolite
2. Unlock the upper horizontal clamp.
3. Rotate the theodolite until the arrow in the upper or lower rough sight points to the feature of interest and lock the clamp.
4. Look through the main eyepiece and use the upper horizontal adjuster to align the vertical lines on the feature of interest.
5. The reading is taken by looking through the small eyepiece. Using the minutes and seconds adjuster set the one of the degrees on the horizontal scale so the single vertical line on the bottom scale is between the double vertical lines under the selected degree.
6. The reading is the degree which has been aligned and the minutes and seconds read from the right hand scale and is the horizontal angle from the reference line.
Process of Measuring Vertical Angles Using a Theodolite
Process of Measuring Vertical Angles
2. Unlock the vertical clamp and tilt the eyepiece until the point of interest is aligned on the horizontal lines. Lock the clamp in place.
3. Looking through the small eyepiece, use the minutes and seconds adjuster to align one of the degrees on the vertical scale with the double lines just below it.
4. The reading is the degree that has been aligned and the minutes and seconds is read from the right hand scale.
5. To complete the reading, it may be necessary to measure the distance from the theodolite to the point of interest.