To make the line of collimation parallel to the axis of the bubble tube. To make of bubble of axis perpendicular to the vertical axis.
Fixing of instrument on tripod
Release the clamp screw of the instrument hold the instrument in right hand and fix it on the tripod by turning round.
Place the instrument in a desired position at a convenient height for sighting with tripod leg spread well a part and tripod sprang as nearly level as can be judge by the eye. When you check bubble is going other side then you touch of opposite leg in clockwise. Pitch by pitch you rounded the legs and check the bubble. Bubble will be come in Centre point.
Place the telescope parallel to a pair of foot screws and bring the bubble to the centre of its run by turning these screws equally either both in wards or both outwards. Turn the telescope through go. So that it lies over the third foot screw and centre the bubble by turning this screw. Bring the telescope back to its original position without reserving the eyepiece and object glass and again bring the bubble to the centre of its run and repeat these operations.
Focusing the eye piece
Remove the lid from the object glass and hold a sheet of white paper in front of it. See whether means of the eye piece simply in its socket, or it has a rotary motion by means of screws threads. Move the eyepiece in and out until the cross hairs and datively seen.
Focusing the object eye piece
Direct the telescope towards the staff and on looking through the eyepiece, bring the image of the staff between the two vertical hairs, of the diagram by lightly topping the telescope. If a clamp and tangent screw are provided by the same should be used.
To make the axis of bubble tube perpendicular to the vertical axis.
To make the line of collimation parallel to the axis of bubble tube.
Means of adjustment are the capstan headed nuts at one and to the tube, connecting the bubble tube to the telescope. If the bubble does not remain in the central position note down the deviation say 2nd division. Bring the bubble half way back by raising or lowering one end of the tube by means of capstan headed nuts and remaining half with the foot screw beneath the telescope.
Turn the telescope through 90 degree so that it lies parallel to the other foot screw and bring the bubble to the centre of its run by means of these screws.
Rotate the telescope and see if the bubble traverses if not repeat the process until the adjustment is correct.
Dumpy Level Sketch