Angular Measurments

Angular Measurments are frequently necessary for the manufacture of interchangeable parts The ships and aeroplanes can navigate confidently without the help of the sight of the land, only because of precise angular measurement.
Angle Standards
In angular measurement , the end standard takes the form of either angle gauges or polygon with the angle defined between adjacent faces. While the line standard takes the form of uniformly defined circles with the lines engraved at regular intervals of say one degree.