Thimble

-      The thimble rotates around a cylinder which is marked in millimeters

-      The left-hand side of the thimble has markings all around it

-      The line labeled 0 is the primary pointer.

Close the jaws

Calculate the least count

Place the object between the two jaws (Anvil andspindle), Spin ratchet until you hear 3 clicks.

Record the position of main scale where the twomeasuring rods met

Note the position of the circular scale whichcoincides with main scale.