The permanent adjustments of theodolites are made to establish fixed relationship between the instrument's fundamental lines.
The fundamental lines or axis of a transit theodolite include the following:- These adjustments once made last for a long time.
The permanent adjustments in case of transit theodolite are:- The horizontal axis must be perpendicular to the vertical axis.
The vertical circle must read zero when the line of collimation is horizontal.
The axis of altitude level must be parallel to the line of collimation.