“A ruler isn’t always straight.” Robert Half
Before there were rulers and fixed distance units, people used distance units based on body parts, like the cubit (length between the elbow and the tip of the middle finger), hand (breadth of a hand) and foot (length of a foot). The cubit was already used by the Egyptians and Babylonians thousands of years ago. The problem with these units was that they varied by era and location.
King Edward ordered during his reign (1272-1307) that the yard and its subdivisions were defined: “It is remembered that the Iron Ulna of our Lord the King contains three feet and no more; and the foot must contain twelve inches, measured by the correct measure of this kind of ulna; that is to say, one thirty-sixth part [of] the said ulna makes one inch, neither more nor less… It is ordained that three grains of barley, dry and round make an inch, twelve inches make a foot; three feet make an ulna; five and a half ulna makes a perch (rod); and forty perches in length and four perches in breadth make an acre.”
Before the 19th century, each country in Europe had its own system of measures and weights, until in 1875 the Metre Convention was signed by 17 nations in Paris and the International Bureau of Weights and Measures (BIPM) was established. Its purpose was to coordinate metrology internationally and the development of the metric system. Other organizations that were created were the General Conference on Weights and Measures (CGPM) and the International Committee for Weights and Measures (CIPM). In 2014 the General Conference counted with 56 Member States, 41 Associate States and Economies and 4 international organizations.
The use of rulers goes back thousands of years, with a ruler found at Lothal (a city of the ancient Indus Valley civilization) dating back to around 2,400 BC. Early rulers were made of ivory or wood, but now they are mostly made of plastic.
- a person (such as a king or queen) who rules a country, area, group, etc.
- a straight piece of plastic, wood, or metal that has marks on it to show units of length and that is used to measure things (source: Merriam Webster).
The English ruler, Spanish regla and Italian riga come from Latin regula, basic principle/rule, ruler.
Dutch liniaal probably comes from French lignal, from Latin linea, line.
Ruler in other languages:
Spanish: la regla graduada
Italian: la riga graduata