Parts of a vernier calipers

A vernier caliper is a precision measuring instruments. It is used to measure up to an accuracy of 0.02mm.The parts of  a vernier caliper fixed jaws(1 and 2) are parts of the beam scale. One jaw is used for taking external measurements, and the other for internal measurements. Movable jaws(3and4):movable jaws are part of the vernier slide. One jaw is used for external measurements, and the other for internal measurements
Vernier slide(5):A vernier slide moves over the beam and can be set in any position by means of a spring loaded thumb lever beam(6):The vernier slide, and the depth bar attached to it, slide over the beam. The graduation on the beam are called the main scale division.depth bar(7):The depth bar is attached to the vernier slide and is used for depth measurement.Thumb lever(8):The thumb lever is a spring loaded lever which helps to set the vernier slab in any position on the beam scale.vernier scale (9):The vernier scale is the graduation marked on the vernier slide. The divisions of this scale are called vernier division.main scale (10):main scale graduations or divisions are matked on the beam.vernier calipers are available in sizes of 150mm, 225mm, 900mm and 1200mm. The selection of the size depends are precision instruments, and extreme care should be taken while handling them. Never use a vernier caliper for any purpose other than measuring. They should be used only to measure machined or filed surface. They should never be mixed with any other tools. Clean the instrument after use, and store it in a box.