Construct a retrograde Vernier scale:

During construct a retrograde Vernier to a scale of 1/5, signify inches and 10^th, and 30 inches and long sufficient to read to mark distance of 11.3 inches on it.

Solution

(a)   Length of primary scale = 1/5 × 30

    = 6 inches.

(b)   Sketch a line 6 inches long and divide it into 30 equivalent parts representing inches, consequently forming a primary scale.

(c)    Set off 11 equivalent parts to the left and above the primary scale and divide it into ten equivalent parts, thus forming a vernier.

(d)   All division of the vernier represents 1.1 inch. Here AB represents the essential distance.