On February 12, 1812, Napoleon Bonaparte issued a decree establishing the 'mesures usuelles,' reintroducing traditional French units alongside the metric system that had been mandated since 1795. Ordinary French citizens, especially merchants and tradespeople, had continued using old units out of habit, and Napoleon's compromise measure acknowledged that the metric system had not yet taken hold.
The metric system had been born from Revolutionary idealism — a rational, decimal system of measurement meant to sweep away the bewildering patchwork of local units that varied from town to town across France, sometimes differing even between neighboring villages for measuring the same commodity. Scientists and reformers hailed it as a triumph of Enlightenment thinking.
But ordinary French people simply refused to give up the units they had grown up with. Bakers, cloth merchants, and farmers continued to think and haggle in terms of the old toise, livre, and pied, finding the new decimal units unfamiliar and impractical for daily commerce.
Napoleon's 1812 decree was a pragmatic retreat, creating hybrid units that referenced traditional names but were redefined in metric terms — a face-saving compromise that lasted until 1837, when the metric system was made fully compulsory again under King Louis-Philippe. The episode is a reminder that even the most rational reforms can founder on the stubbornness of everyday habit.
Key people: Napoleon Bonaparte