The cubit is an ancient unit based on the forearm length from the middle finger tip to the elbow bottom. Cubits of various lengths were employed in many parts of the world in antiquity, during the Middle Ages and as recently as Early Modern Times. The term is still used in hedge laying, the length of the forearm being frequently used to determine the interval between stakes placed within the hedge. The Biblical cubit is approximately 18-21.8 inches, the Greek cubit is approximately 18.3 inches, and the Roman cubit is approximately 17.5 inches.

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