Using a Vernier Caliper

A vernier caliper is a measuring device commonly used in scientific labs and other industries where there is a need for very precise measurements. The vernier adds an extra digit of accuracy to a measurement for great precision. It is a great device to use when measuring the outer diameter of cylinder or round object. It is also useful in measuring the inner diameter of a cylindrical object and the depth of a hole.
A vernier caliper is L-shaped, with a movable auxiliary scale. The moveable scale can slide freely along the length of the fixed ruler. The movable arm can slide in order to fit an object in between for a measurement. Some calipers have smaller movable auxiliary scales in order to take internal measurements.
Vernier calipers consist of two scales. It consists of a main scale which is engraved on a fixed ruler. The vernier, which is the secondary scale, slides along the main scale as was already described.
Make sure the vernier is closed and properly zeroed. The first mark of zero on the main scale is aligned with the first mark on the movable scale. To take a measurement you must look for the mark on the fixed scale which is just to the left of the zero on the vernier caliper. That reading will be the first measurement. Then look to see which mark on the vernier comes closest in alignment with the mark on the fixed scale. This reading will be the secondary measurement.
Reading a vernier caliper is pretty easy to learn. Since the vernier is very precise the error rate is generally very low, especially since they have locking screws which allow people to lock the movable scale in place so that the vernier caliper can be closely examined without worrying about disturbing the object. Vernier scales are easy to read because the human eye will notice whether two line segments are aligned properly. Vernier acuity is the ability by a person to detect the proper alignment of two line segments. In most people, Vernier acuity is particularly high, allowing one to accurately differentiate between aligned and misaligned marks on a Vernier scale.
A vernier caliper like most scientific instruments needs to be well maintained. Always make sure that the vernier is calibrated properly. When the movable arm is closed, the zero on the vernier scale should line up with the zero on the main scale. If it does not, the device needs to be serviced so that the two lines are aligned properly.