Humans have used parts of the body as tools ofmeasurements, for instance, the forearm, hand, and finger. Theword “foot” is still in use. The word “calibration” joined the English language within the last century, and it was used mainly in defense. But throughout history, calibration existed already in the ancient civilizations of Egypt, Mesopotamia, and the Indus Valley. The excavations carried out in these regions have revealed the use of angular graduation for civil engineering.