How to read a staff surveying?

A levelling staff is a straight rectangular rod having a black and white graduation of 5 mm. It is used to determine the amount by which the station is above or below the line of sight, and reading is done by means of a telescope.

Notations on staff: –

• There is a red mark at each decimeter
  Each decimeter length is divided into 20 graduated strips by alternate black and white spaces of 5 mm thick.
• A staff reading consists of 4 digits.
• The first digit represents the whole number of meters; the second digit represents decimeters; the third digit represents centimeters, and the fourth digits represent millimeters.

Reading of Levelling Staff: –

• The staff reading is the reading on the staff at which the horizontal cross-hair cuts the staff.
• Thus, if we say that a staff reading is 1.340, it means the horizontal cross-hair cuts the staff at, 1 meter, 3 decimeter,4 centimeter and 0 mm.
• It appears inverted, when the staff is seen through the telescope. So, when the staff is held on the ground, it should be read from above downwards.