Measurements with odolite is optical means. Measurement with passometer, measurement with pedometer, pacing are based on method of measuring distances directly.

Magnetic Declination is a horizontal angle between true meridian and magnetic meridian. Arbitrary bearing of a line is horizontal angle which it makes with Arbitrary Meridian through one of extremities of line.

To Unfold chain, chainmen keeps both handles in right hand and throws rest of portion of chain in forward direction with his right hand. The or assists in removing knots etc and in making chain straight.

It also transfers points from line ranger to ground. Spirit level is instrument used to level plane table by adjusting spirit bubble in it to center.

True bearing of a line is horizontal angle which it makes with true Meridian through one of extremities of line. Compass needle will be parallel to magnetic meridian. Angle measured always keeping magnetic north as a reference is called magnetic bearing.

Each band is 20 cm deep. It is used on occasion of rod that can be used for rough measurement of short length.

By working from whole to part, it is possible to eliminate errors and to localise errors. Orwise, it might expand in magnitude.

Iron can easily spoil due to rusting. Steel, Invar, linen tapes are long lasting and have protective layer.

For exploring mineral wealth mine surveying is used. Determining points of strategic importance is military surveying.

80 Gunter?s chains = 1 mile. Length of each Gunter?s chain is 66ft. 5280 ft is approximately equal to one mile. Therefore, to measure one mile distance 80 Gunter chains are required.