Accuracy and Precision and Theodolite

A theodolite is a survey testing instrument used for measuring horizontal and vertical angles. A basic theodolite usually consists of a small sized telescope linked with mechanisms to measure horizontal and vertical angles. It has several moving parts and is quite heavy. The theodolite telescope is fixed within perpendicular axes- the vertical axis and the horizontal, or trunion, axis. The instrument is fixed on a base that can be rotated on a tripod by a leveling system. The angle to the desired point can be measured by pointing the telescope towards that particular point. The angle thus obtained can be then read on the telescope scale.

What is Theodolite Used For?
Theodolite is one of the major instruments used in surveying and engineering work. In recent times, theodolites are used for many other specialized tasks too like in meteorology and rocket launch technology.

Types of Theodolite
Various theodolite types are used for surveying and other specific purposes. Some of the types of theodolite include the following.

Repeating Theodolite- In this type of theodolite, several angle readings are taken on a graduated scale. The average angle measurement is then derived by dividing the accumulated sum readings by the number of observed readings. The results of repeating theodolites are reliable enough. However, this type of theodolites are confined for locations where the support is not stable or where space for using other such instruments is limited.

Direction Theodolites- In this type of theodolite, the circle is arranged to be fixed while the telescope is aimed on a number of signals. Readings on the circle are for every direction. These theodolites are very good option for triangulation purpose.

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Transit- This is a specialized type of theodolite has a telescope that can "flip over" ("transit the scope") to let easy back-sighting and doubling of angles for error reduction. Some transit instruments are capable of reading angles directly to