The manual vernier caliper

The vernier caliper is a precision instrument that can be used to measure internal and external distances extremely accurately. There is also the manual version vernier caliper. Measurements are interpreted from the scale by the user. This is more difficult than using a digital vernier caliper which has an LCD digital display on which the reading appears. The manual version has both an imperial and metric scale.
Manually operated vernier calipers can still be bought and remain popular because they are much cheaper than the digital version. Also, the digital version requires a small battery whereas the manual version does not need any power source.
EXAMPLE 1: The external measurement (diameter) of a round section piece of steel is measured using a vernier caliper, metric scale.

A. The main metric scale is read first and this shows that there are 13 whole divisions before the 0 on the hundredths scale. Therefore, the first number is 13.
B. The�?hundredths of mm�?scale is then read. Only one division on the main metric scale lines up with a division on the hundredths scale below it, whilst others do not. In the example below, the 41st division on the hundredths scale lines up exactly with a division on the metric scale above.
C. This 41 is multiplied by 0.02 giving 0.82 as the answer (each division on the hundredths scale is equivalent to 0.02mm).
D. The 13 and the 0.82 are added together to give the final measurement of 13.82mm (the diameter of the piece of round section stee)l.