Protractor on the dial from 180°, as the dial is graduated from opposite zero marks to 90° each way. Since the spaces, both on the main scale and the Vernier scale, are numbered both to the right and to the left from zero, any angle can be measured. The readings can be taken either to the right or to the left, according to the direction in which the zero on the main scale is moved. Reading the Vernier scale: The bevel protractor Vernier scale may have graduations of 5′ (minutes) or 1/12°. Each space on the Vernier scale is 5′ less
Scale of chords the centre point of this line. For a circle of radius , each half will be formula_1 so the chord will be formula_2. The line of chords scale represents each of these values linearly on a scale running from 0 to 60. It appears on Gunter's scale and the Foster Serle dialing scales. The commercial company Stanley marketed a metal version (Stanley 60R Line of Chords Rule) in 2015. Scale of chords A scale of chords may be used to set or read an angle in the absence of a protractor. To draw an angle, compasses describe an arc from