Before revision: The line of collimation or line of sight should coincide with axis of the telescope.Surveying by Dr. B.C Punmia and Dr Ashok Kumar JainThe line of sight should also be perpendicular to the horizontal axis at its intersection with the vertical axis .
After revision: The line of collimation or line of sight should coincide with axis of the telescope.Surveying by Dr. B.C Punmia and Dr Ashok Kumar Jain The line of sight should also be perpendicular to the horizontal axis at its intersection with the vertical axis .