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Measuring Weight and Distance

Why do countries use different systems of measuring weight and distance? The reason is because, historically, a variety of systems for measure and weight evolved in different geographical regions. The use of pounds and ounces in England and the U.S. to measure weight goes back a long way in history.

Systems of Measuring Weight

In the eighth and ninth centuries of the Common Era, Arab civilization flourished in the Middle East and Spain. The Arabs were skilled mathematicians, and they used coins as units of weight – a minted coin could not easily be cut or shaved to reduce its weight.

The Arabs used a coin called a silver Dirhem as the basic measure of weight – it was roughly equivalent to 45 grains of barley. Ten dirhems made a "wukryeh," and this was translated into Latin – the language used in most of Europe – as an "uncia." That's where we get the word for "ounce."

The Arabs traded with all the countries of Europe. In the "Hansa" cities of northern Germany, a region of great shipbuilding and trading, a pound was established as equal to sixteen ounces, or 7200 grains of silver.

This was the standard adopted in Great Britain in the eight century, but King Offa, who ruled the country at the time, ran out of silver!

So he reduced the pound to 5400 grains of silver, and it stayed that way until the Norman King William came from France and conquered England. King William set up samples of the pound and the ounce in the Tower of London, where he could be sure they wouldn't be tampered with.

Anglo-Saxon countries have used pounds and ounces ever since to measure weight. The British pound sterling, or GBP, was equal to one pound weight of silver in King Offa's time.

But, when Queen Elizabeth I ruled England in the 16th century, the Avoirdupois weight system was adopted. This was a form of measure traditonally based on the weight of coal. The name derives ultimately from French avoir de pois ("goods of weight" or "property"). The avoirdupois pound contains 7,000 grains, or 256 drams of 27.344 grains each, or 16 ounces of 437 1/2 grains each. It is used for all products not subject to apothecaries' weight (for pharmaceutical items) or troy weight (for precious metals). Since 1959 the avoirdupois pound has been officially defined in most English-speaking countries as 0.45359237 kilograms.

In Asia, very different systems of measuring weight evolved. In Ancient India, a measure of weight called the "Satamana" was equal to the weight of 100 Gunja berries.

In China, the first emperor Shi Huang Di created a system of weights and measures in the third century Before the Common Era. The basic weight was called the shi, and was fixed at about 60 kilograms (132 pounds); the two basic measurements, the Chi and the Zhang, were set at about 25 centimeters (9.8 inches) and 3 metres (9.8 feet), respectively. And the Chinese came up with a special way to ensure accuracy. A special size of bowl was used for measurements, and it not only had to be of a certain size, but, when you struck it, it had to make a specific sound. If it didn't hit the right pitch, the measurement was off.

The Metric System – Weight and Distance Together

In Europe, the modern metric system was developed first in France by two astronomers, Jean-Baptiste Delambre, and Pierre Mechain, at the end of the 17th century.

Based on their labors, in 1790, the Prince de Talleyrand proposed a bill to the French Assembly to establish the metric system as the unified system of measurement for the country. The French National Academy of Sciences was tasked with its definition.

The Academy created a system that was, at once, simple and scientific.

The unit of length was to be a portion of the Earth's circumference. Measures for volume were to be derived from the unit of length, thus relating the basic units of the system to each other and to nature.

What made the system particularly attractive was that larger and smaller multiples of each unit were to be created by multiplying or dividing by 10 and its powers. This made it very easy to use.

The Commission assigned the name meter to the unit of length. This name was derived from the Greek word metron, meaning "a measure." The physical standard representing the meter was to be constructed so that it would equal one ten-millionth of the distance from the North Pole to the equator along the meridian running near Dunkirk in France and Barcelona in Spain.

The initial metric unit of weight, the "gram," was defined as the mass of one cubic centimeter (a cube that is 0.01 meter on each side) of water at its temperature of maximum density. A kilogram is a thousand grams.

The cubic decimeter (a cube 0. 1 meter on each side) was chosen as the unit for capacity. The fluid volume measurement for the cubic decimeter was given the name "liter."

By 1900, a total of 35 nations -- including the major nations of continental Europe and most of South America -- had officially accepted the metric system. The U.S. is one notable exception.

Systems of Measuring Distance

The same is true of the U.S. in its use of the "mile," as opposed to the kilometer (a thousand meters). The U.K. officially recognizes the kilometer, but if you buy a car there, the spedometer will give the speed in miles per hour.

The mile and the foot all come to us from ancient Rome, where measurements were based on the number 12. For example, the 12 divisions of the Roman "pes," or foot were called unciae. Our words "inch" and, as we have seen, "ounce" are both derived from that Latin word. The Latin word "mila," on the other hand, was based on the measure of one thousand paces by a Roman legion. The mile today is equal to 1,760 yards (approximately 1.609 kilometers). It was adopted in England by Queen Elizabeth I in the 16th century.

The "yard" as a measure of length can be traced back to early kings of England. They wore a piece of clothing around the waist that could be removed and used as a convenient measuring device. The word "yard" comes from the Saxon word "gird" meaning the circumference of a person's waist.

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