Where Does the Metric System Come From?
Where does the metric system—that staple of scientific experiments, SAT problems, and soda bottles—come from? Who invented it, when, and for what purpose? Read below to find out!
The metric system is a system of measurements. While the metric system was invented relatively recently, in some ways, it resembled measurement systems that predated it. For instance, it was deigned to work within size ranges of materials that people usually encounter.
The invention of the metric system was mostly meant to improve on some troubles faced by earlier systems of measurement. One problem was that many of the early systems of measurement were far less precise than we would expect from a measuring system today. Something rather generic—like the time a peasant needed to till a fill or a man’s arm span—were both units of measurement used in early modern Europe, but of course these units vary between individuals. A second problem was that units of measurement were rarely consistent, changing not only from country to country but also from town to town. In early modern France, for instance, researchers have estimated that there may have been 250,000 different units of measurement. Different systems of measuring distance and weight clearly would be a problem for trade and governance, and would affect other areas, such as mapmaking. Finally, a problem with earlier systems was that they were not decimalized, meaning that smaller and bigger divisions of these measurement were not multiples of 10.
The issue of decimalization can seem difficult, but in fact, we are all very familiar with it because our current system of measuring time is not decimalized. Take an hour, for example. An hour is the main unit for measuring time. To get to smaller units like a second or a minute, we need to use conversion factors of 60 and 3600. But time is not decimalized because the smaller units do not evenly divide to create decimals. Take the example of 2.5 hours. 2.5 hours is not 2 hours and 50 minutes. It is instead 2 hours and 30 minutes. Instead of looking at the decimal and seeing how many minutes are left over, I have to convert this decimal to minutes using the conversion factor. It was this complicated conversion system that the metric system also was designed to do away with.
These problems with measurement systems existed for centuries. And several reformers in early modern Europe had suggested ways to fix the issue. But it was the metric system that would finally be introduced to definitilvely deal with these issues.
The metric system was invented at the end of the 1700s in France. In the 1700s, attitudes were changing within Europe about the importance of science, mathematics, rationality, and exactitude, in a period known as the Enlightenment. The Enlightenment reshaped Europe: it changed ideas about governance, roles in society, the importance of science, and education. One of these changes also included new ideas of exactness of measures.
It would take the French Revolution, however, for these ideas to move from scientific musings into law. After the establishment of the new French Republic in 1792, the new republican government officially instituted the metric system and formalized it in the country’s legal system. There were 6 units, which included the meter (length), gram (mass), franc (currency), and liter (liquid volume). Larger or smaller amounts of these units could be created through the addition of Greek prefixes, like ‘kilo’ for 1000. These measurements, decimalizations, and their approximate value formed the basis of what would become the metric system, although only meters and (kilo)grams remain standard measurements in the metric system today.
Standard versions of these measurements were provided so that cities and regions could confirm that their measurements were still conforming to the universal standard. While most of these standard meter lengths (known in French as mètre étalons) are no longer extant, in Paris, for instance, there is still one of the original meter measuring sticks.
Measurements of distance and weight were not the only suggestion of what should be decimalized during the French Revolution. The revolutionaries also sought to decimalize time. Time has many of the same problems as other early units of measurement: there are 60 seconds in one minute, 60 minutes in one hour, and 24 hours in one day. There’s no easy way to tell what fraction of a day 2000 seconds are, without doing some conversions first. Some revolutionaries suggested a similar decimalization of time: that there should be seconds, minutes, and hours that were all evenly divisible into a 10-hour day.
After the French Revolution (around 1792), the government of France also attempted to introduce a decimalized system of time. This system worked very much like how the metric system worked. Each day consisted of 10 hours; each hour consisted of 100 minutes; each minute consisted of 100 seconds. Because the length of a day is determined by external environmental factors, the length of a second had to be adjusted to fit these new conversions. A minute became around 14% shorter, while an hour then became around 2.5 times longer. Whereas the metric system remains with us today as one of the main units used across the globe, the decimalization of time, however, did not catch on.
Over the following decades, the system of measurements in France gradually became adopted elsewhere on the European continent, leading to wider universal systems of measurement and to greater commitments to the importance of having a system of weights and measures that was widely accepted.
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