Which of the following statements is NOT true for precise levelling when compared to ordinary levelling?
1
High grade levels and stadia rods are used in precise levelling.
2
Two rodmen are employed and backsight and foresight are taken in quick succession.
3
Length of sight is limited to 100 m in length.
4
Rod readings are taken against the two horizontal hairs of the diaphragm.
5
None of the above