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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:   

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 

using the words "metric system" and see what you can find.

Does this help?

-Doctor Sarah,  The Math Forum
 Check out our web site!   

Associated Topics:
Middle School History/Biography
Middle School Terms/Units of Measurement

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