Tag Archive for Tag: Back Sight

Tag: Back Sight Terms Used in Direct Method of Levelling

The following terms are used in direct method of levelling: (i) Plane of Collimation: It is the reduced level of plane of sight with respect to the datum selected. It is also known as ‘height of instrument’. It should not be confused with the height of telescope from the ground where the instrument is set. (ii) Back Sight (BS): It

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