Explain the three temporary adjustment of a dumpy level.(6 marks)June/July 2020

A dumpy level is a surveying instrument that is used to determine the elevation of points on the ground. It consists of a telescope mounted on a tripod, and it is leveled by adjusting the tripod legs until the bubble in the level vial is centered. To make a temporary adjustment to a dumpy level, the surveyor will need to make small adjustments to the position of the instrument to account for any deviations from true level. This process is known as “setting the level.”

Here is the general procedure for making a temporary adjustment to a dumpy level:

1. Level the tripod: The surveyor will first ensure that the tripod is level by adjusting the length of the legs until the bubble in the level vial is centered. This will provide a stable base for the instrument.
2. Set the instrument: The surveyor will then set the instrument on the tripod and adjust the position of the telescope until it is level. This is typically done by adjusting the position of the eyepiece using the focusing knob.
3. Check the bubble: The surveyor will then check the bubble in the level vial to ensure that it is centered. If it is not, the surveyor will make small adjustments to the position of the instrument until the bubble is centered.
4. Check the readings: The surveyor will then take a series of level readings using the instrument, and will check the readings to ensure that they are accurate and consistent. If any readings are off, the surveyor will make further adjustments to the position of the instrument until the readings are satisfactory.
5. Record the adjustments: The surveyor will record the final position of the instrument and any adjustments made to it in the field book, along with the readings taken. This information will be used to make any necessary adjustments to the final survey data.