Invention of the Metric System
Date: 02/13/97 at 12:21:38 From: Arlene Margagliano Subject: Metric question Dear Dr. Math, Our math teacher says that a group of scientists from around the world convened to invent the metric system. However, our French teacher told us that the French devised the metric system. We would like to know which teacher is correct. Can you help us? Thank you, Heather and Gemma
Date: 02/13/97 at 13:19:17 From: Doctor Sarah Subject: Re: Metric question Bonjour Heather et Gemma, Here's some information on the web about the way the metric system came about from the daily science radio series Earth and Sky: http://www.earthsky.com/1995/es951113.html Most people on Earth nowadays use a common system of measurement. The modern metric system, called the SI, has become the primary means of measuring the world around us. The original metric system was invented in France at the end of the 18th century. The French Academy of Sciences proposed a reformation of the official units of measure. Until then, standards varied widely from one province to the next, and even from village to village. This presented an enormous barrier to efficient trade - both within France and with other parts of the world. The first step in defining the new metric system was to determine a base for the system's units. The metric reformers decided to make it a decimal system, which means it uses a base of 10 for all its numbers. That seemed to be a logical choice since many cultures have used 10 as the basis of their number systems - probably because we humans have ten fingers and ten toes. The first unit in the new decimal system was for length or distance. A team of researchers spent several years carefully measuring the distance between two points on Earth at sea level. From this measurement, they determined the distance from the north pole to the equator. This distance - one fourth the circumference of Earth - was then divided up into 10 million parts and each part was called a meter. So you could say that Earth's circumference was 40 million meters - not far from today's value. So the metric system was born with a single unit - a meter. (That's about a yard for those who still use an older system of measurement.) A centimeter is one-hundredth of a meter. Each centimeter is about four tenths of a standard inch. The meter makes it possible to measure not only length but also volume - the amount of space in a given container, like a box or an office building. And with a way to measure volume, the inventors of the metric system could branch out into other units of measurement. They next tried to establish a world unit to describe how much an object weighs. They chose to combine the natural properties of water with their unit for volume. Water was readily available all over Earth, so scientists in other countries could easily produce their own weight standards. They decided to call the weight of one cubic centimeter of pure water at a given temperature a gram. But weight is an intrinsically unreliable measurement. You'd weigh less on the moon than on Earth, for example, because the moon is smaller and less massive than Earth - its gravity doesn't pull on you as much. A physicist would say that a more reliable measurement is that of mass - how much matter your body contains. Because science experiments have to be reproducible anywhere, the kilogram - a thousand grams - came to be used as the standard of mass, not weight, around the world. ______________________________________ It turns out that BOTH of your teachers were right, more or less. A group of scientists did convene to work out the metric system, it just happened that these particular scientists belonged to the French Academy of Sciences, so they were French (so they didn't come from all over the world). Do you know about the issues surrounding converting to the use of the metric system in the United States? For information, search AltaVista: http://altavista.digital.com/ using the words "metric system" and see what you can find. Does this help? -Doctor Sarah, The Math Forum Check out our web site! http://mathforum.org/dr.math/
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