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well. The theodolite's basic features for measuring horizontal angles
are:
 A horizontal circle, graduated in degrees, which may be
rotated and then clamped in any position;

 A circular plate which may be rotated inside this circle, and
which shows additional graduations for reading the graduations on the
circle with greater precision;

 A telescope which is attached to this circular plate and turns
with it, and which can also be turned up and down in the vertical
plane.
 A tripod (three-legged support) on which is placed the

theodolite when measuring.

Task 3. Answer the questions, using the active vocabulary.

1. Why are horizontal and vertical angles so important for
surveying?
2. What are horizontal angles? How are they used?
3. Can you name modern horizontal angle measurement methods?

Which is the most useful to your mind?
4. What instruments can be used for angle measurement?

Task 4. Define whether the following statements are true or
false. Correct the false ones according to the text.

1. Horizontal angle is the difference between 2 intersecting lines

when they are projected onto the datum plane.
2. 1 degree = 90 minutes (90').
3. 1 minute = 90 seconds (90").

4. A theodolite is sometimes called a transit.
5. Most theodolites are designed to measure only horizontal
angles.
6. A tripod is a four-legged support on which the theodolite is

placed.

Vertical angles

Task 1. Read and memorize the following words and word-
combinations:

vertical angle – вертикальний кут;
angle of elevation or depression – кут підвищення чи

пониження;
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