British contributions to the metric system

The development of the metric system was a truly international effort. The British have made substantial contributions to its development. The metric is in effect an English invention. Metrication was first proposed by an Englishman, the Reverend John Wilkins in 1668. British scientists have been at the forefront of developing the metric system, and many have given their names to metric units, including Newton, Faraday, Joule, Kelvin and Watt.

John Wilkins includes a chapter called “Measure” in his book, “An essay towards a real character, and a philosophical language”. This chapter contains a blueprint for a universal decimal system of measurement with many similarities to the metric system. For length, Wilkins has a base unit called the Standard. He redefines traditional unit names for subdividing the Standard, using the foot as one-tenth of the Standard, the inch one-hundredth and the line one-thousandth. For multiples of the Standard, the pearch (sic) is redefined as 10 Standards, the furlong as 100 Standards and the mile as 1000 Standards. Similarly, he redefines traditional unit names for weight so that they relate to one another by powers of ten and he does the same for volume unit names.

John Wilkins explains how a pendulum could be used to define the Standard, something that was seriously considered for defining the metre. He proposed that the Standard would be a universal measure. For measures of capacity, he proposed that the cubical content of this Standard may be called the Bushel. For measures of weight, he proposed that this cubical content of distilled rainwater be the Hundred. Here we see remarkable similarities with the design of the metric system. In the metric system, the metre is the basic measure, which is used to derive measures of volume/capacity and mass/weight. The litre is the volume/capacity of a cubic decimetre (tenth of a metre), and a kilogram was originally defined as the weight of a litre of pure water at a temperature of 4 °C.

In 1861, a committee of the British Association for Advancement of Science (BAAS) including William Thomson (later Lord Kelvin), James Clerk Maxwell and James Prescott Joule introduced the concept of a coherent system of units which is fundamental to the modern metric system. They proposed the metre, gram and second as base units. They also developed the application of the metric system in the fields of electricity and magnetism. The BAAS insisted that electrical units should be coherent with the metric system and that electrical and mechanical energy should have the same unit. In 1873, a BAAS committee proposed centimetre, gram, second (CGS) base units using prefixes from micro to mega. The committee made proposals for electrical units. They also proposed a unit of electrical resistance (later named the ohm).

Several metric units were named after British scientists. These are the scientists and the units that were named after them:

  • Isaac Newton – the unit of force is the newton (N)
  • James Joule – the unit of energy (or work or amount of heat) is the joule (J)
  • Michael Faraday – the unit of capacitance is the farad (F)
  • James Watt – the unit of power (radiant flux) is the watt (W)
  • William Thomson, Lord Kelvin – the unit of thermodynamic temperature is the kelvin (K)
  • Louis Gray – the unit of absorbed dose of specific (imparted) energy is the gray (Gy)
  • John Dalton – the standard atomic mass is the dalton (Da)

In more recent times, Richard Brown, the head of metrology at the UK’s National Physical Laboratory, proposed the new SI prefixes beginning with R and Q (ronna, quetta, ronto, quecto) in respond to the unofficial use of prefixes for data storage such as brontobytes and hellabytes. The problem with these unofficial prefixes is that they did not fit into the SI naming scheme, and they started with letters that were already in use for existing prefixes or for other units. The new metric prefixes were approved in November 2022.

Sources and further reading:

8 thoughts on “British contributions to the metric system”

  1. I don’t get why people were bothered about where the metric system is invented in the first place. Loads of things in common usage where invented in all kinds of places but that doesn’t stop them from being widely adopted. The metric system is objectively the better system in comparison to what came before and there is simply no good justification for retaining older units in certain situations.

    Never mind that there is nothing especially British about imperial units. They are just simply older units that were introduced by various invaders and were similar to the ones that were phased out in mainland Europe.

    Liked by 1 person

  2. @Alex M if there’s one thing we all should have learned in the last decade (if not longer) is that no amount of evidence will win an argument if somebody has believed what they saw in a fun post on social media. That and ‘fundamental nationalism’ makes people believe ‘traditional = good’ and ‘new = bad’ regardless of what might be sensible or right.

    As much as I want to avoid politics, the things that keeps us messing about with imperial measures are the very same things that gave us Trump, Johnson and Brexit. We can but hope that now that people have had a taste of these things that they might start to question where they’re getting their information and change for the better might come.

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  3. Alex M:

    I agree that it doesn’t matter so much where the metric system was first proposed in the first place, but it is important to point out the massive input from British scientists, with seven units named after these scientists (as mentioned in the article). It seems ludicrous that as a nation we should still not properly be using the system that we were at the forefront of developing.


  4. Alex M:
    Here is a little story about what happened some years ago (about 40 I think). I was in a small DIY shop and was buying a metre rule and a length of timber, which I specified in metres. Another customer fired up with a tirade against the metric system. “We beat them in the war,” he said. “Why should we change to their system?” During our verbal exchange, the shopkeeper looked on with a broad smile, which gave the message, “I’m not getting involved in this; I just give customers what they want.”
    This illustrates the thinking of that time – many people thinking of the metric system as a foreign invasion. I believe the thinking came not from history but from common observation. In this country we use feet an miles; across the Channel and beyond they use metres and kilometres. Few people are interested in, or aware of, who invented the various units.
    Nowadays, metrication is largely accepted, and a scene like this in a shop is unlikely to happen.
    Free Thinker:
    Yes, the only real obstacle to completion of metrication is ancient laws, which the government seems reluctant to repeal.


  5. The United Kingdom did not sign the Treaty of the Metre in 1875, but waited until 1884 to do so. This did not stop Johnson Matthey from supplying the prototype kilogram in 1879 and 40 replicas in 1884. Thus it was that the International Prototype Kilogram (IPK) was “Made in England”.

    By the start of the twenty-first century, the IPK was showing its age and a new definition of the kilogram was needed. The new definition was based on the Planck Constant and the recommended technique for measuring this constant was to use the Watt Balance, developed by Bryan Kibble at the National Physical Laboratory in Teddington. After Kibble died in 2016, the Watt Balance was renamed the Kibble Balance in his honour. Again, the definition of the kilogram use equipment that was “Made in England”. The original Kibble Balance has since been sold to the Canadians.

    I think that this is another example of British scientists leading the way, only to be held back by the British politicians.

    Liked by 1 person

  6. Speaking of being held back by politicians, the election Ronald Reagan as US President instead of Jimmy Carter was the death knell for metrication in the USA, which would have proceeded if Carter had been elected. In that event the UK would have had no choice but to finish metrication in order to survive in the global economy that would be universally metric.

    Liked by 1 person

  7. One small hopeful sign is the number of YouTube videos and nature documentaries I have seen in the last couple of years that either include metric alongside Imperial (even in American productions) or that even sometimes use metric exclusively (again, even in American productions but also in British productions). This is a big change from a number of years ago but seems to be more or less limited to “science-y” kinds of videos and programs. Still, it is a step in the right direction.

    Liked by 1 person

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