**History of the Metric System**

**Christopher A. Ervin**

Vista Grande High School

Vista Grande High School

INTRODUCTION

WHO USES METRICS

Use of Metrics

Science and technology both require a great deal of measurement. The scientific community worldwide realized long ago a real need for standardization of all the units of measure. It was largely because of this standardization need that the metric system was developed. Today, every major nation in the world and the vast majority of all nations, have officially adopted the metric system.

The United States is the ONLY major exception. We continue to use the Customary, or English system, which dates back to about the 1200’s.

WHAT IS “METRICS”?

The metric system is a group of units used to make any kind of measurement, such as length, temperature, or weight.

No other measurement system equals the metric system in its simplicity!

The scientists who created the metric system designed it to fit their needs.

The metric system is both logical and exact. But a non-scientist needs only know a few metric units to make everyday measurements.

WHY SWITCH?

The metric system may seem difficult to those of us who have not grown up using it, but that is mainly because of unfamiliarity with the units. The rest of the world has made the switch without any major problems, and we can too. This is because metrics is SIMPLE. In fact, it is far more simple than our present system. First, it follows the decimal system – that is metric units increase or decrease by units of 10. For example, one centimeter has 10 parts called millimeters, and 100 centimeters make 1 meter. Under the customary or English system there is NO single relationship. Example, feet go by 12 inches but yards go by 3 feet. The second reason for its simplicity is that there are only 7 basic units that make up all measurements. The customary/English system has more than 20 basic units just for its common measurements. Customary/English units used for special purpose add many more units to that system.

HISTORICAL BACKGROUND

Earliest Measures

Experts theorize that the earliest units of length were derived from parts of the body. Units of capacity probably had the same beginning. The problems with this are obvious. Different size people result in different size measurements. Man realized early that a standard system of weights and measures was necessary. Officials, either government or religious, became the setters and keepers of the standardization for different societies. Still the diversities continued. Both Greek and Roman civilizations made attempts at standardization and yet neither were entirely successful, with dual systems resulting in both empires. None of the systems they developed were entirely logical.

EARLIEST MEASURES

Some weights were derived from natural sources such as grain, others from the weight of a particular cube. Another weakness of logic in some areas was the tendency to mix two or more systems of numbers in one system of weights and measures. Then, as now, there are 4 systems of numbers in use in different places and for various purposes; the decimal system of units subdivided by tenths, the duo-decimal system in which factors of twelve are used, the binary system of halves and quarters, and the sexagesimal system and it is based on sixties. The decimal system reportedly comes from the Chinese and Egyptians, the duo-decimal system from the Romans, the binary from the Hindus, and the sexagesimal from the Sumerians and Babylonians.

HOW AND WHY METRICS CAME ABOUT

Confusion in the European system of weights and measures was well established by the time the Roman Empire collapsed. The Dark Ages probably caused a regression from any semblance of standardization that existed. By the Middle Ages the number of local units of weights and measures had become almost limitless. The crude systems of the Middle Ages continued throughout the world without much question until about the 16th or 17th century, when scientists started demanding something better. By the end of the 18th century, scientists had created the metric system. While there was sentiment in both England and America for standardization, it was the political climate of France that allowed it to happen. The basic concept of the metric system was not new in the 1790’s.

HOW AND WHY METRICS CAME ABOUT

Scientists such as France’s Mouton, England’s Tallyrand, and America’s Franklin, had developed theories based on the decimal system. The main hold up seemed to be agreement on a fundamental unit. In the end, the lineal system was to be one ten millionth of the meridian distance between the pole and the equator as determined by survey. In 1795 France passed an act legalizing the metric system. The names, it was agreed, would be polysyllabic in which Greek prefixes would be affixed to denote multiples and Roman prefixes to denote subdivisions.

MULTIPLES AND SUBDIVISIONS

Myriameter 10,000 m

Kilometer 1,000 m

Hectometer 100 m

Decameter 10 m

Meter Base Unit = 1

Decimeter 0.1 m

Centimeter 0.01 m

Millimeter 0.001 m

Similar prefixes are applied to units of weight and capacity. Liters (l) and Grams (g)

HOW AND WHY METRICS CAME ABOUT

There are two important points of simplicity. Its basic units of weight and capacity were directly related to the fundamental linear unit; the liter was a cubic decimeter and the gram, the weight of a cubic centimeter of water.

All of the secondary units are multiples or divisions by 10 of the basic units. All that is needed to know is the size of a meter, the relationship between meters and units of capacity and mass, and the meaning of the prefixes. Memorizing of arbitrary and unrelated units such as miles, feet, and acres was now unnecessary.

PROGRESS ONCE DEVELOPED

Although it was official, the real acceptance was very gradual. The acceptance of the system in other European countries has taken even longer. A conference in France in 1870 attended by 15 nations, including the United States, led to the signing in 1875 of the “Metric Convention”. A treaty under which the International Bureau of Weights and Measures was established. The bureau still resides in suburban Paris, and is still the world center of metrology.

During the twentieth century most other nations of the world officially adopted the metric system. The United States is still the only remaining MAJOR nation that has not officially converted to the metric system. I have to say here that there is not one single country in the world that uses a pure form of the metric system for all of its transactions of weights and measures.

Intent of this Unit

The purpose of this unit is to advance your knowledge of the metric system and advancing the cause of teaching the metric system.

With the understanding of the metric system will come increased understanding of science and technology since these fields, and many others, already operate in the metric system.

Most of us in teaching today did not grow up learning the metric system. For many of us our first contact has come with the introduction of metrics into our curriculum's and textbooks. Thus, there is probably resistance among those of us who teach just as there is among the general population (you).

PROGRESS ONCE DEVELOPED

The most common variation is the continued use of old names for metric units. Another common departure from the true metric system is the application of the binary number system to metric units.

An example of this would be to call the equivalent of a pint of milk a half liter. THIS IS NOT CORRECT.

In countries that have been on the metric system for any length of time, the non-metric instances are few and far between. Most people that live by the metric system and their younger generations do not know any other way.

PROGRESS ONCE DEVELOPED

Since the establishment of the International Bureau of Weights and Measures, some changes have been made to the metric system, most of them are only of interest primarily to scientists and engineers. The standard of the second has been redefined and prefixes have been added for both multiples and subdivisions to help extend the scale of measurement. The prefix “tera” before any of the base units means trillion, “giga” means one billion, and “mega” means one million. The following prefixes have been added for subdivisions; “micro” means one millionth, “nano” means one billionth, and “pico” means one trillionth. At its 1960 meeting, the International Convention, which meets every 6 years, interpreted the metric system into the System International d’Units, for which the abbreviation is S.I. and is used in all languages now.

PROGRESS ONCE DEVELOPED

For all purposes other than scientific and advanced technical work this is merely a name change. Actually, it is a purification and extension of the metric system to make it truly universal.

Through the years, several systems had developed which were all metric but differed in detail in various parts of the world. The S.I. also formalized the extension of the metric system to seven base units.

PROGRESS ONCE DEVELOPED

The basic units of the S.I. system are:

Length Meter (m)

Mass Kilograms (kg)

Time Seconds (s)

Electric Current Ampere (A)

Temperature Kelvin (K)

Luminous Intensity Candela (cd)

Amount of Substance Mole (mol)

In addition to the base units the S.I. system includes a number of derived units for measurement of such things as force, energy, and power. The unit for force is the “newton” (N) which is defined as the amount of force that, acting for 1 second on 1 kilogram of matter, will increase its speed by one meter per second. Named for the English formulator of the Law of Mechanics, it is, appropriately, just about the gravitational force acting on an average falling apple.

PROGRESS ONCE DEVELOPED

Energy has many forms, but all energy is basically the by-product of force and distance, and is convertible from one form to another. Thus, the S.I. system uses one unit for all kinds of energy; the Joule (J) which is the amount of energy needed to push a distance of one meter against a force of one Newton.

CONCLUSION

These derived units, as well as the ampere, the Kelvin, the candela, and the mole are of use to scientists and engineers, but not of much concern to most people.

Conclusion

Measures of length, weight, and capacity are the commonly used ones. The most commonly used metric units of length in everyday life are the millimeter for small dimensions, the centimeter for daily practical use, the meter for expressing dimensions of larger objects and short distances, and the kilometer for longer distances. The most convenient unit of volume for everyday use is the liter (l), although it is part of the S.I. system only in that it is recognized as a name for the cubic decimeter. One liter is slightly larger than the U.S. quart. Precise measurements of volume in science are expressed in cubic centimeters (cm3) or cubic millimeters (mm3).

Conclusion

The most common unit of mass or weight is the kilogram (kg) which equals about 2.2 pounds. Grams (g) and the metric ton (t) are also used.

To the general public, most of the history, and all but the more basic units of the metric system are unnecessary. Some background and at least a basic awareness of all the components of the metric system are useful for those of us who will use it in school.