Category: 2. Levelling

Line of collimation or principal line of sight: It is the imaginary straight line joining the optical center of the objective glass with the point of intersection of the crosshairs of the diaphragm.Bubble tube axis: It is an imaginary line on the longitudinal curve at the midpoint of the tube. It is also called bubble…

With self-reading staff, readings can be taken faster than with target staff.In the case of target staff, the services of trained personnel are essential.Reading can be more sophisticated with target staff. But if the crewman does not direct the line of sight correctly to bisect the target, it gives a much clearer reading. The surveyor…

Care should be taken to keep the leveling staff truly vertical during the reading. To hold the staff in a vertical position, the person holding the staff should stand with their heels behind the staff, the heel of the staff between their feet, and hold it in their hands at face height. When the level…

The target staff consists of two rods, which slide over each other. The two bars are held together by brass clamps. Extending the sliding can increase the length of the staff. The face of each rod is graduated in feet, tenths, and hundredths of a foot, while the back of the sliding rod is similarly…

It is made up of three pieces. The top piece is 1.25 m long solid, while the 1.25 m long central piece and 1.5 m long bottom piece are hollow. The top part slides into the central part through the telescope. The staff has a total length of 4 meters when fully extended. The upper…

The folding staff is made of well-finished wood. It is 4 meters long and consists of two sections, each 2 meters long and connected together. The width and thickness of the staff are kept at 75 mm and 18 mm respectively. The foot of the staff is provided with a brass cap to prevent wear…

They are usually 3 meters long. Owing to the absence of hinges or sockets on these staffs, greater accuracy in reading can be obtained, but on the other hand they are inconvenient to carry in the field. The use of concrete personnel is generally limited to precision surface work.

A staff on which the readings are read directly by the observer through the telescope is called a self-reading staff. Self-reading staffs are of three types as discussed below.

A straight rectangular wooden rod graduated in meters/feet and further smaller parts is called a leveling staff. The bottom of the leveling staff represents the zero reading. The reading given by the line of white on a leveling staff held vertically is the height of the line of collimation above the point on which the…

It is easy to construct with few moving parts. It requires less constant adjustment. Adjustments once made last for a long time.