The comment by Han Maenen on the previous article reminds us that this is the 200th anniversary of a decree which ended temporarily the use of the metric system for everyday purposes in France and elsewhere.
Wikipedia provides an account of the introduction in the French Empire of mesures usuelles, a compromise between the metric system and traditional measurements: http://en.wikipedia.org/wiki/Mesures_usuelles
Some UK readers may find some aspects of the story familiar.
In brief, the introduction of the metric system into France in the late 1790’s was poorly managed. This, combined with lack of understanding, made it unpopular. Many people still thought in non-decimal terms using the fractional subdivisions of the old system. Napoleon saw the difficulty of gaining general acceptance for a decimal system of measures and introduced a ‘half-way-house’ system of measurement, mesures usuelles, for use in retail. His decree implementing this change was dated 12 February 1812. Government continued to use the metric system and it was taught at all levels of education.
Pre-revolutionary had France ‘enjoyed’ a wide diversity of measures. Contemporaries estimated that under the cover of some eight hundred names, ancient regime France contained a staggering 250 000 different units of weights and measures. These had been swept away by the revolution, just as the UK Weights and Measures Act of 1824 swept away many of Britain’s medieval measures. Napoleon was left with no option but to define mesures usuelles in terms of the prototypes of the metre and the kilogram, a precedent followed much later in the US in 1893 and in the UK in 1963. As an example of the new system, the toise was defined as two metres, just as the Imperial yard is now defined as 0.9144 metres, and was divided into 6 new pieds and 72 new pouces.
Some ask if the UK should follow even further in the steps of Napoleon. After all, the UK has now adopted several of the features of mesures usuelles, including the definition of imperial measures for length, mass and volume in terms of metric standards, and an attempt to run two measurement systems in parallel – the “very British mess” with which we are familiar.
Ronnie Cohen writes (perhaps with tongue in cheek):
“Napoleon’s policy enabled traditional unit names to live on. Perhaps we can try something like this in the UK. Let’s see how British imperial unit names can be redefined and fixed in rational metric sizes. We can redefine the main imperial unit names as follows: metric inch = 2.5 cm, metric foot = 25 cm, metric yard = 1 m, metric fluid ounce = 25 mL, metric pint = 500 mL, metric gallon = 5 L, metric ounce = 25 g, metric pound = 500 g.
The metric pound would directly correspond to the French livre and would be very similar in size to some of the historical pounds that were once used in parts of Europe. The metric pint (500 mL) would be almost the same size as the US liquid pint (473 mL), albeit slightly bigger. These units would just be redefined to be rational metric sizes. The old definitions would be abolished.
The advantage of this approach is that consumers who want to continue to use the words ‘pounds’ and ‘pints’ could do so.”
UKMA takes the view that compromises such as these would complicate and prolong the metric changeover, and should be avoided. The country needs one system of measurement, not two . Successive UK Governments have made many mistakes during the metric transition, but thankfully ‘mesures usuelles’ have not been among of them.
History too has not treated mesures usuelles kindly. No other country took up the idea, the decimal metric system was re-introduced permanently in the Low Countries in 1820, and the system of mesures usuelles was dropped in France on 1 January 1840.
It was, arguably, the Swiss that paid the highest price for Napoleon’s bright idea. During the French Revolutionary War, Switzerland had been refashioned by the French as the Helvetian Republic. By 1812, its transition to the metric system was almost complete. Mesures usuelles saw to it that Switzerland reverted to its old measures, and its changeover to metric was not resumed until the 1870s.
But the most interesting question relating to mesures usuelles is perhaps that put by Han Maenen in his recent comment on Metric Views: Would the US have avoided its current measurement muddle, Mars Orbiter, Route I-19 and all that, if Napoleon and France had persevered with the introduction of the decimal metric system beyond 1812?