# Can vernier scale ratio be less than 1?

I came across a question (See Image) that states about two vernier scales

1. The first vernier scale is the top-most figure in the image: It has 10 vernier scale division equal to 9 main scale division (according to question, read the 2nd sentence). This mean it has vernier scale ratio equal to 10:9 or >1.
2. The second vernier scale is the bottom-most figure in the image: It has 10 vernier scale division equal to 11 main scale division (according to question, read the 2nd sentence). This mean it has vernier scale ratio equal to 10:11 or <1. Here my doubts arouses.

My father states that in a standard manufactured vernier callipers, less number of main scale division will always be equal to higher number of vernier scale division, or in other words, vernier scale ratio is always greater than 1.

I need clear-cut answer that whether the second vernier scale drawn in bottom of image is not practically possible or whether there is no constraint on vernier scale ratio, that is it is possible that vernier scale ratio maybe less than 1.

• Actually the bottom one is a little easier to read ...
– rob
Commented Jun 12, 2016 at 20:37

You do not even need $C_2$ in order to convince yourself that it is possible. Just take $C_1$ and turn it upside down so that it is 9:10 instead of 10:9.
On the other hand, in terms of human usability it is rational to have the ratios all going the same way ($>1$), so that all vernier callipers work in the same direction.