Aquaculture Engineering

Self reading staff -Telescopic staff

Unit 1- Surveying

Levelling Staff

Self reading staff

Telescopic staff

It is arranged in three telescopic lengths. When fully extended it is usually of 14ft length. The 14 ft staff has solid top length 4’6” sliding in to the central box of 4’ 6” length. The central box in turn slides into the lower box of 5’ length. In the 5 m staff the three corresponding length are usually 1.5, 1.5 and 2 m.

The levelling staves graduated in English unit generally have whole number of feet marked in red to the left side of the staff. The odd lengths of the feet are marked in black to the right hand side. The top of these black graduations indicates the odd length, while the bottom shows the even length. The hundredth feet are indicated by alternate white and black spaces, the top of a black space indicating odd hundredth feet and top of a white space indicating even hundredth. Some times when the staff is near the instrument the red mark of whole foot may not appear in the filed of view. In that case the staff is raised slowly until the red figure appears in the field of view, the red figure thus indicating the whole feet.