It is the scale on a micrometer.
The modern vernier caliper reads to thousandths of an inch
The least value which can be measured from any measuring instrument or device is called its least count. Generally the least count of a vernier caliper is 0.02mm.You can get a least count of 0.01mm in Digital vernier caliper.
The zero correction of a vernier scale is the adjustment needed to align the zero mark of the vernier scale with the zero mark of the main scale when there is no object being measured. It accounts for any offset or error in the alignment of the two scales to ensure accurate measurements.
Pierre Vernier
I guess it is found by vernier as it works on vernier theory -Manasa
Because they were invented by Pierre Vernier in 1631.
where on the vernier caliper would you read to obtain the vernier scale reading
To read a measurement on a micrometer, observe the main scale and the Vernier scale. The main scale represents the whole millimeters, while the Vernier scale indicates the fraction of a millimeter. The measurement is obtained by combining the values shown on both scales where they align.
The 9 divisions on the main scale correspond to a length equal to 10 divisions on the vernier scale because the 10 divisions on the vernier scale cover a distance that is slightly shorter than the 9 divisions on the main scale. This difference enables the user to make more precise measurements by comparing the alignment of the two scales to determine the measurement with greater accuracy.
It is to minimize the error percentage of parallax. Also we can easily identify if the spectrometer has been moved beyond 270 degrees If we take readings on two scales and then average of it, the value would be more accurate
Adam Vernier is 6' 2".
Ruben Vernier is 5' 10".