France – and the majority of the rest of the world – is marking 150 years since the Metre Convention first united them in a shared language of measurement, laying the foundations for international scientific cooperation.
Issued on: 25/05/2025 - 17:15
Modified: 25/05/2025 - 17:20
There aren't many 136-year-old metal cylinders tucked away in Paris basements that can claim global fame.
Yet "Prototype 35" – a shimmering iridium-platinum artefact – quietly changed the course of modern life.






