Explain temporary adjustment of dumpy level?
1 Answer

The following are the different steps to be followed in a temporary adjustment

1. Selection of suitable position- A suitable position is selected for setting the level. From this position, it should be possible to take the greater number of observation without any difficulty and the ground should be fairly level and firm.

2. Fixing level of tripod stand- The tripod stand is placed at a required position with it leg well apart and press firmly into the ground. The level is fixed on the top of the tripod stand according to the fixing arrangement provided for that particular level. It should be remembered that the level is not to be set up at any station.

3. Approximate levelling by a leg of tripod stand- The foot screw is brought to the centre of their run. Two legs of tripod stand are firmly fixed into the ground .then the third leg is moved left or right in or out until the bubble is approximately at the centre of its run.

4. Perfect levelling by foot screw- As the longitudinal bubble is on the top of the telescope the latter is placed parallel to any pair of foot screw. (i.e. first position) and the bubble is brought to the centre by turning the foot screw equally either both inward and both outwards. The telescope is then turned through 900 and brought to a third foot screw and bubble is brought to be centre by turning this foot screw clockwise or anticlockwise the telescope again brought to its original position and the bubble is brought to the centre.

Dumpy level

5.focusing the eyepiece- a piece of white paper is held in front of the object glass and the eyepiece is moved in or out by turning it clockwise or anticlockwise until the crosshair can be seen clearly.

6. Focusing the object glass- the telescope directed toward the levelling staff. Looking through the eyepiece the focusing screw is turned clockwise or anticlockwise until the graduation of the staff is distinctly visible and parallax is eliminated.

7. Taking the staff reading- finally, the level of the instrument is verified by turning the telescope in any direction.

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