Paris, 20 May, 1875, representatives from 17 countries signed an historic agreement, the Convention of the Metre. Now celebrated every year as World Metrology Day, it paved the way for the International System of Units (abbreviated to SI), the world’s most widely used system of measurement and provided a standardised way to quantify just about anything you need to measure.
This year marks the 150th anniversary of the Convention of the Metre, and the theme seems especially pertinent: Measurement for all times and all people.
Whenever you look at your watch, stand on the measuring scale, glance at the speedometer on your car, and a million and one other daily occurrences, you’re directly benefiting from the International System of Units (SI). The SI provides the foundation for precise and consistent measurements across the globe, touching every aspect of our lives.
For all times…
The Earth’s rotation gives us one of the most basic of all measurements, the perception of time. The change from day to night is one of the most fundamental and unifying measurements. There was no need for an international act of diplomacy to agree on the length of a day.
Other early units of measurement were famously based on parts of the body. In the imperial system, the yard was the length from the tip of the nose to the end of an outstretched arm. An inch was the length of a thumb. The cubit is an even older measurement going back to the ancient world. It was based on the length of an arm from the elbow to the tip of the finger. Until these units of measure were standardised, there was significant variation, not least of all because no two human beings are exactly the same size.
The curious case of the cubit…
The term “cubit” has come to mean an incredible range of units of measure since its beginnings in the ancient world. Archaeologists have found “cubit” rods from ancient Egypt dating back to 2700 BC.
There’s the Assyrian “standard” cubit measuring around 51cm, the “big” cubit measuring 56cm and the “cubit of the king”, reserved for Royal purposes, at 55cm. There’s the biblical cubit, the ancient Greek cubit, the Roman cubit, and then there’s the Islamic world.
Get ready for this. There’s the legal cubit, the black cubit, a different King’s cubit, the cloth cubit, the small cubit (at 60cm making it larger than the Assyrian “big” cubit), the Hashemite cubit (also known as the Basran cubit), the carpenters’ cubit, the architects’ cubit… and the list goes on.
Depending on where you’re from (and when), a cubit might be anywhere from 40cm up to about 70cm!
We’ve written about unusual measurement units previously on the Manufacturing Intelligence blog.
For all people…
As science progresses, measurement techniques have become more sophisticated, more precise and accurate. But at the heart of it all are the ideals of collaboration, standardisation, fairness and equality.
An early attempt at standardisation is evident in a now obscure measurement unit from Anglo Saxon England. Known variously as the “rod” or the “perch”, it was determined by measuring the length of the feet of the first sixteen men leaving church on a Sunday morning. We’ve come a long way since then, and one of the purposes of World Metrology Day is to celebrate that fact.
The Convention of the Metre ensures consistency in measurement and fairness in trade. The idea behind it goes back much further than that. Here in the UK we have documented evidence of this dating back nearly 1000 years.
Here’s the Magna Carta (1215):
“There is to be one measure of wine and ale and corn within the realm… and one breadth of cloth and it is to be the same with weights”
And here is an even earlier Royal declaration, the “Assize of Measures” (1196):
“Throughout the realm there shall be the same yard of the same size”
Underpinning it all is the desire to prevent disputes, promote collaboration and improve quality of life for everybody. Metrology provides a foundation for fairness in society. Because of that it represents something more than just numbers and measurements.
World Metrology Day celebrates a concept that goes beyond cultural and geographical boundaries
The 7 standard units – the meter, kilogram, second, ampere, kelvin, mole, and candela — are the building blocks of innovation. They ensure that whatever we’re measuring we are all speaking the same language.
These units and the Convention of the Metre (now expanded from 17 signatories up to 50), is more than a few complex definitions on a piece of paper:
The metre is the length of that path travelled by light in a vacuum during a time interval of 1/299792458 of a second.
Between the lines of those words is 1000s of years of scientific thought and experimentation. They cross international boundaries as if they were just arbitrary lines on a map. No matter who you are, what nationality, race or religion, the Convention of the Metre is a unifying force in a divided world.
Happy world metrology day.
Click here for more information about Hexagon’s contribution to the field of metrology.
