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Amgueddfa Cymru
15" inside calipers. Two arched legs with common joint considting of a rivet and end washers, the legs cross over each other slightly. The outside calipers are used to measure a variety of objects. The leg of the caliper would be held around one side of the object being measured while the other leg was rocked back and forth about the first leg which was used as a pivot. The calipers were then transferred to a straight rule and the equivalent distance read off.