Gyro-Theodolite
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The gyrotheodolite is a theodolite used for surveys which do not have sky visibility (mining, underground survey). This instrument gives the orientation of the [[true North (the direction of Earth's rotational axis) which is set as a reference for future underground observations.
The gyro-theodolite is composed of a theodolite with a gyroscope on it. We obtain the true North by:
- Orienting approximately the theodolite to the North (about minutes of arc)
- A power supply activates the rotation of the gyro spinner.
- The gyro will oscillate through the North meridian until reaching the direction of the true North (considered to be a point of minimum potential energy).
When the gyro stabilized the reading on the horizontal circle of the theodolite is equivalent to North.
