The true meridian passing through a station on surface of the earth is the (imaginary) line of intersection of a (imaginary) plane passing through the geographical North and South poles of the earth with its actual surface. The direction of true meridian at any station is constant and hence, direction of a line with reference to this remains same over time. At any station, it can be determined through Astronomical survey. For any engineering works of importance, the direction of at least one line is determined with true meridian as reference.

<< Back