The upper or lower horizontal crosshair visible in the telescope of a level or transit. They are spaced at a precise ratio from the center crosshair. By reading the interval on a leveling rod between the upper and lower stadia hairs, a surveyor can calculate the distance from the instrument to the rod.
I can't read the top stadia hair because of those branches, just give me a half-interval reading from the center.
Taking a half-stadia reading (measuring between the center hair and one stadia hair) and doubling it is a common workaround when an obstruction blocks a full reading.
Also heard as
- stadia wire
- stadia line
Related terms
Stadia
A traditional optical method for measuring distances and elevations using a graduated rod and a telescope.
Level staff
A graduated measuring rod used with a leveling instrument to determine elevation differences.
Jigger
A casual slang term used by survey crews to refer to a total station or a theodolite.