How are measuring units related to the human body?
In all traditional measuring systems, short-distance units are based on the dimensions of the adult human body. The inch represents the width of a thumb; in fact, in many languages, the word for “inch” is also the word for “thumb.” The foot (12 inches) was originally the length of a human foot, although today it is longer than most people’s feet. The yard (3 feet) is the name of a 3-foot measuring stick in England, but it is also approximately the distance from the tip of the nose to the end of the middle finger of the outstretched hand. Finally, if you ask an adult to stretch their arms out to the sides as far as possible, their total “arm span,” from one fingertip to the other, is called a fathom (6 feet).Other early measures were derived from physical activity, such as a pace, a league (the distances that equaled an hour’s walking), an acre (the amount of land plowed in a day), a furlong (the length of a plowed ditch). The ell, based on the distance between the elbow and the index finger, was used to measure out cloth. It ranged from 20 to 91 inches (0.513 to 2.322 meters) depending upon where it was used and the type of goods measured.