Metrication - Before The Metric System

Before The Metric System

For more details on this topic, see History of measurement.

In the Roman empire a foot measure pes was used, divided in 12 parts unciae ("inches"). The libra ("pound") was an other of many measures that had wide effect on European weight and currency long after Roman times, e.g. lb, £. The meaning came to differ a lot with time. As several others, Charlemagne launched reform programmes of various kinds, and intended to standardise units for measure and currency in his empire, but there was no real general breakthrough.

In medieval Europe, local laws on weights and measures were set by trade guilds on a city-by-city basis. For example, the ell or elle was a unit of length commonly used in Europe, but its length varied. It was 40.2 centimetres in one part of Germany, 70 centimetres in The Netherlands and 94.5 centimetres in Edinburgh. A survey of Switzerland in 1838 revealed that the foot had 37 different regional variations, the ell had 68, there were 83 different measures for dry grain, 70 measures for fluids and 63 different measures for "dead weights". When Isaac Newton wrote Philosophiae Naturalis Principia Mathematica in 1687, he quoted his measurements in Parisian feet so readers could understand the size. Examples of efforts to have local intercity or national standards for measurements include the Scottish law of 1641, and the British standard Imperial unit system of 1845, which is still commonly used in the United Kingdom. At one time Imperial China had successfully standardised units for volume throughout its territory, but by 1936 official investigations uncovered 53 dimensions for the chi varying from 200 millimetres to 1250 millimetres; 32 dimensions of the cheng, between 500 millilitres and 8 litres; and 36 different tsin ranging from 300 grams to 2500 grams. However, revolutionary France was to produce the definitive International System of Units which has come to be used by most of the world today.

The desire for a single international system of measurement derives from growing international trade and the need to apply common standards to goods. For a company to buy a product produced in another country, they need to ensure that the product will arrive as described. The medieval ell was abandoned in part because its value could not be standardised. It can be argued that the primary advantage of the International System of Units is simply that it is international, and the pressure on countries to conform to it grew as it became increasingly an international standard. However, it also has simplified learning as the units are based on the metre, just using decimal based prefixes to cover all dimensions, instead of new names with ratios of 3, 12 etc., as the figures are kept the same and easy to add or multiply. Also scientific measurement and calculation are greatly simplified as units for electricity, force etc. are metric based according to the SI system (e.g. 1 Joule=1 kgm2/s2=1 VAs). Standardisation of measures has contributed significantly to the industrial revolution and technological development in general. SI is not the only example of international standardisation; several powerful international standardisation organisations exist for various industries, such as the International Organisation for Standardisation, the International Electrotechnical Commission, and the International Telecommunication Union.