Explanation

 Main feature: Allows precise line of sight adjustment without moving the entire instrument.

Explanation

 Held by hand or with a bubble level attached to ensure verticality.

If tilted, the reading becomes longer and inaccurate.

The staff person may use a plumb bob or circular bubble for precision.

Explanation

 A 14-foot three-piece staff means it has 3 equal sections.

Explanation

 Quick and efficient

Doesn’t require communication between two people

Ideal for differential levelling

Explanation

 Purpose: Measures vertical distance from the instrument line of sight to the ground.

Material: Usually made from aluminum or fiberglass; lightweight and durable.

Length: Generally 4 to 5 meters (around 13 to 16 feet), often telescopic for easy transport.

Types:

Self-reading staff (most common)

Target staff (has a sliding target for precise reading)

Explanation

 Taken on a known point (like a benchmark).

It’s the starting reading for a new instrument setup.

Used to determine the height of the instrument (H.I.).

Explanation

 Taken on a Change Point (CP)

Marks the end of a level setup.

Used to calculate the reduced level before moving the instrument.

Explanation

 It's the location where the level is set up to take readings.

Chosen for clear sightlines to staff points.

Must be stable and roughly level for accuracy.

Explanation

 Used when shifting the level instrument to a new position.

Ensures continuity in levelling.

Acts as a reference between two setups of the instrument.

Explanation

 One central cross-hair and two stadia hairs (one above and one below).

Used in tachometry to measure distance indirectly.

The distance between the stadia hairs helps calculate the horizontal distance to the staff.