Levels
 Details of Construction
 Tilting Level
 Dumpy Level
 Automatic Level
 Levelling Staff
 Setting Up An Instrument
 Errors/Calibration

Errors/Calibration

The main source of instrumental error in levels is known as collimation error as it effects the line of sight, also known as the line of collimation.  The error occurs if the line of sight, indicated by the cross hairs in the eyepiece of the telescope, is not parallel to the horizontal when the instrument is levelled. The test that we undertake in order to determine the amount of error and then eliminate it from measurements is known as the two peg test.

Two Peg Test Method

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