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As people began to travel farther from their homes for trading and other business purposes, the need for measurement standards became increasingly important. This is the story of the creation of the meter, now the accepted standard of length measure almost everywhere in the world.
Philippe Theys
Data Quality Manager
For hundreds of years, there were as many units of measurement as there were communities in the world. Groups of people developed their own systems independently, based on objects or phenomena that they considered important. Many of these systems were based on units used by the Babylonians, Egyptians, Greeks, or Romans.
By the 17th century, people from locations around the world began to do business with each other. They found that different measurement systems greatly complicated any trading activity or real estate transaction. For scientists the plethora of units of length posed particular problems. Accurate length measurements were important for a better understanding of the universe and of our planet. The solution: the “invention” of a standard unit of measure. Thus the meter was created.
The concept was first proposed in the late 17th century. But it took almost 130 years to go from the idea of a universally accepted reference length to an accurate definition of that length. Along the way, the process involved fields of knowledge as diverse as surveying, astronomy, geometry, experimental physics, and metrology. Interestingly enough, even psychology and politics played a role in the adventure. Here’s the story.
The development of a universal reference of measure started in 1670. Gabriel Mouton, the vicar of St. Paul’s Church in Lyon, France, suggested the adoption of two standard reference lengths. The first he called the milliare, which was defined as a one-minute arc of the Earth’s meridian. This equals 1/60 of a degree, one part in 360 of a full circle, or one part in 180 of a half circle. Mouton called the second standard reference the virga, which corresponded to 1/1,000 of a milliare. The idea of making the length of a meridian the reference could not displease anybody, since it did not favor any country, nation, or king. The idea seemed simple enough, but it did not catch on right away.
Confusion over standards continued. The term toise was used to describe a standard of measure in France. But the actual length of a toise varied from department (a large county within France) to department.
Between 1730 and 1740, two large expeditions were launched to confirm the shape of the Earth, and prove that it is a spheroid. One went to what was then called Peru (today Ecuador) and used the “Peru toise” as its standard of measurement. The other headed to Lapland (today Sweden and Norway) with a standard of the “Lapland toise.” These important scientific expeditions reinforced the need for a universal standard of measure.
About 100 years after Mouton proposed his idea, it received political support from the Revolutionary National Assembly of France. The assembly issued a decree in 1791, which read: “In order to achieve the uniformity of weights and measures, it is necessary to set a natural and invariable unit of measure. The only means of extending this uniformity to foreign countries and of committing them to a new measuring system is to choose a unit which has nothing arbitrary or peculiar to the situation of one people of the world. The Assembly adopts the length of a quarter of a terrestrial meridian as a basis of the new system of measurements.”
The French Academy of Sciences accepted the decree, and thus one meter was set as equaling a 10-7 quarter of the Earth’s meridian. To put it more simply, the meter is 1/10,000,000 of the distance from the North Pole to the equator along a meridian. |
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