Surveying
To avoid large centering error with very short legs, observations are generally made

By using optical system for centering the theodolite
To chain pins
All listed here
To a target fixed on theodolite tripod on which theodolite may be fitted easily

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Surveying
For mapping any country

Primary triangles are broken down into secondary triangles of somewhat lesser accuracy
All listed here
Geodetic triangulation of greatest possible sides and accuracy is carried out
Secondary triangles are further broken into third and fourth order triangles, the points of which are used for detail surveys

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