History
The earliest caliper has been found in the Greek Giglio wreck near the Italian coast. The ship find dates to the 6th century BC. The wooden piece already featured a fixed and a movable jaw. Although rare finds, caliper remained in use by the Greeks and Romans.
A bronze caliper, dating from 9 AD, was used for minute measurements during the Chinese Xin dynasty. The caliper had an inscription stating that it was "made on a gui-you day at new moon of the first month of the first year of the Shijian guo period." The calipers included a "slot and pin" and "graduated in inches and tenths of an inch."
The modern vernier caliper, reading to thousandths of an inch, was invented by American Joseph R. Brown in 1851. It was the first practical tool for exact measurements that could be sold at a price within the reach of ordinary machinists.