4. Retell the text into native language:
A horizontal angle is the difference in direction between: (1) two intersecting lines in a horizontal plane; (2) two intersecting vertical planes; or (3) two intersecting lines of sight to points in different vertical planes. It is measured in the horizontal plane in degrees of arc. Horizontal angles usually are measured clockwise but may be measured counterclockwise. Angles are usually measured by transit. An interior angle is on the inside of an enclosing figure, and an exterior angle is on the outside of an enclosing figure. A deflection angle is that angle which any line extended makes with the succeeding or forward line. The direction of the deflection is identified as "right" or "left." An angle-to-the-right is the clockwise angle at the vertex between the back line and forward line (fig. 1-1).
A vertical angle is the difference in direction between a horizontal plane and an intersecting line, plane, or a line of sight to a point. It is measured in the vertical plane in degrees of arc. Measurements are referenced "up" or "down" from the horizontal as "plus angles" or "minus angles."
Describe pictures using the information from the text
Lesson 11
1. Match the words with their translations:
Peg -
Hand -
Crosswire - ,
Adjustment - ,
Level -
Arc -
Screw -
Mirror -
Bubble -
2. Read and translate the text into native language:
Hand Levels
To adjust a hand level, hold it alongside an engineer's level that has been leveled and sighted on some well-defined point. The line of sight of the hand level should strike the same point when the bubble is centered. If it does not, adjust the hand level. A quick way to determine if the hand level is in adjustment is to stand in front of a mirror and look through the hand level at the mirror. If you can see your eye looking back at you through the level it is in adjustment. Adjust the Locke level by means of the screw at one end of the level tube. The screw moves the crosswire, which defines the line of sight.
Set the index site of the Abney level at zero on the graduated arc. Then raise or lower one end of the level tube until the bubble is centered. The two peg method of adjustment, as described for the dumpy level, may also be used.
3. Answer the questions:
1. What is the difference between hand level and engineers level?
2. What role does the bubble in the level play?
3. What is the quick way to determine the adjustment of the level?
4. By the means of what can you adjust the Locke level?
5. Name the methods used in level adjustment.
