A system of measurement is a set of units which can be used to specify anything which can be measured and were historically important, regulated and defined because of trade and internal commerce. Scientifically, when later analyzed, some quantities are designated as fundamental units meaning all other needed units can be derived from them, whereas in the early and most historic eras, the units were given by fiat (See Statutory law) by the ruling entities and were not necessarily well inter-related or self-consistent.
Although we might suggest that the Egyptians had discovered the art of measurement, it is only with the Greeks that the science of measurement begins ...view middle of the document...
Nor were they necessarily the same units (or equal units) between different members of similar cultural backgrounds. It must be understood by the modern reader that historically, measurement systems were perfectly adequate within their own cultural milieu, and the understandingthat a better more universal system (based on more rationale and fundamental units) only gradually spread with the maturation and appreciation of the rigor characteristic of Newtonian physics. Moreover, changing a measurement system has real fiscal and cultural costs as well as the advantages that accrue from replacing one measuring system with a better one.
Once the analysis tools within that field were appreciated and came into widespread use in the emerging sciences, especially in the applied sciences like civil and mechanical engineering, pressure built up for conversion to a common basis of measurement. As people increasingly appreciated these needs and the difficulties of converting between numerous national customary systems became more widely recognised there was an obvious justification for an international effort to standardise measurements. The French Revolutionary spirit for took the first significant and radical step down that road.
In antiquity, systems of measurement were defined locally, the different units were defined independently according to the length of a king's thumb or the size of his foot, the length of stride, the length of arm or per custom like the weight of water in a keg of specific size, perhaps itself defined in hands and knuckles. The unifying characteristic is that there was some definition based on some standard, however egocentric or amusing it may now seem viewed with eyes used to modern precision. Eventually cubits and strides gave way under need and demand from merchants and evolved to customary units.
In the metric system and other recent systems, a single basic unit is used for each fundamental quantity. Often secondary units (multiples and submultiples) are used which convert to the basic units by multiplying by powers of ten, i.e., by simply moving the decimal point. Thus the basic metric unit of length is the metre; a distance of 1.234 m is 1234.0 millimetres, or 0.001234 kilometres.
Metrication is complete or nearly complete in almost all countries of the world. US customary units are heavily used in the United States and to some degree Liberia. Traditional Burmese units of measurement are used in Burma. U.S. units are used in limited contexts in Canada due to a high degree of trade.
A number of other jurisdictions have laws mandating or permitting other systems of measurement in some or all contexts, such as the United Kingdom – where for example the traffic sign regulations (TSRGD) only allow distance signs displaying imperial units (miles or yards) – or Hong Kong.
In the United States, metric units are widely used in science, military, and partially in industry, but...