1 A chronological history of the modern metric system (to 2008) Throughout all of history there have been people who have given time, energy, and money to help our measuring methods become more rational, sensible, and above all, more honest. Thanks to these people, gone are many of the countless, daily opportunities for the strong to injure the weak, for the smart to cheat the simple, and for the rich to take advantage of the poor. Much of this success is due to the system based on a 'universal measure' that was first described by John Wilkins in London. Go to the article Commentary on ‘Of Measure’ by John Wilkins for a better understanding of how the work of John Wilkins, AN ESSAY Towards a REAL CHARACTER, And a PHILOSOPHICAL LANGUAGE (1668), fits into an historical context. Wilkins’ Essay shows that the metric system and the International System of Units (SI) both had their origins in England in 1668. The subsequent development of the metric system in France in the 1790s was also heavily influenced by thinkers from the USA, especially Benjamin Franklin (1706/1790), Thomas Jefferson (1743-1826) and George Washington (1732/1799). The desire for a universal measure was voiced by many scientists and philosophers throughout history. John Wilkins called it a desiderata, and Condorcet said that the metric system, based on the universal measure of a metre, was for all people, for all time. These people knew that a universal measure would help trade, communication and science, and by cutting all confusion due to multiple measuring words would foster understanding between people and nations. Agreed, accurate, and precise measuring standards for length, mass, volume, and time that can be used equally across communities have been a vital need in the development of all societies since the evolution of agriculture and the growth of large scale communities and economies. Every attempt that has been made to agree on an arbitrary human measure as the standard, such as thumbs, hands, spans, feet, paces … has always been defeated by the problem of human pride. It is well known that if three men meet together to decide on a standard foot, then each of them will insist that his foot should become the standard foot. On a larger scale, if three nations meet to agree on a standard foot and each of the three already have feet that are different in length, then even though all three agree that having an agreed standard foot will benefit all of them, the question they ask is, Which of our leaders will be chosen to have the model for a new standard foot? Throughout history no-one has resolved this difficulty. Note: in 2008, the various states of the USA have yet to resolve whether they will use the international foot or the statute foot; some use one, some use the other, and some use both. 2 John Wilkins recognised, in 1668, that creating a new, universal measure that was derived from nature was the only way to replace local measures without local disputes. Wilkins’ universal measure is now the basis of the modern metric system. The quantification of land, goods, building materials, and the system for recording the figures are now much easier, more accurate and more precise. This applies to all human activities such as trade, construction, agriculture and ownership. It is intended that this timeline will give you information about the important dates and events in the development of The International System of Units (SI), and also a feel for the life and times at various stages in the history of the metric system and of the SI. This timeline includes some experiences with the metric system from many nations, but with more details from Australia, the United Kingdom (UK), France and the United States of America (USA). The Australian experience is included as a successful example of metrication, and the UK is included as an unsuccessful example of metric conversion, despite the fact that the concept for a 'universal measure' first arose in England. France and the USA are included because they are respectively the first and last nations on Earth to legally adopt, promote, and widely use the metric system. Because of the metric system, the whole world is now able to communicate through common ways of measuring. We can share the same perceptions of space, dimensions, and mass. As an example, when two farmers from two different countries met, they used to find it hard to understand each other when the conversation touched upon miles, arpents, chis, ells, or toises, for each would have different magnitudes in mind, but they understand each other without difficulty when talking of metres, litres, or kilograms. 15 000 000 000 before the Common Era (BCE) The metric system has given us simple methods to handle very large numbers, very small numbers, and all of the other numbers in between. Here is the biggest example. The 'Big bang' theory of the Universe is based on the observation that all the stars and galaxies in the Universe seem to be moving away from each other. If you calculate their speeds of separation, you can calculate that the Universe might have begun with a 'Big Bang' 15 000 000 000 years ago. We observe the speeds using light, so 15 000 000 000 light years in each direction indicates that we are at the centre of a sphere with a radius of 15 000 000 000 light-years; it follows that the diameter is 30 000 000 000 light-years. As light travels nearly 9 500 000 000 000 kilometres in a year, this means that the diameter of the Universe is approximately: 30 000 000 000 years multiplied by 9 500 000 000 000 kilometres per year which equals 285 000 000 000 000 000 000 000 000 kilometres This is a very large number and before the metric system was developed, people – even scientists and mathematicians – had difficulty saying or writing such big numbers. These days we simply say that the diameter of the Universe is about 285 yottametres. Note: According to NASA (http://map.gsfc.nasa.gov/universe/uni_shape.html): We now know (as of 2013) that the universe is flat with only a 0.4% margin of error. This suggests that the Universe is infinite in extent; however, since the Universe has a finite age, we can only observe a finite volume of the Universe. All we can truly conclude is that the Universe is much larger than the volume we can directly observe. The calculation above (written prior to 2008) has been left in as a demonstration of the use of SI for large numbers. Editor 4 500 000 000 BCE The Earth formed as part of the solar system. 3 200 000 BCE The first traces of humans appeared on the Earth. 5000 BCE The earliest known reasonably uniform methods of weights and measures seem to have arisen some time after 5000 BCE. These appear to have been used by the people of Egypt, Elam (now in Iran), Mesopotamia (now in Iraq and surrounding areas) and the Indus Valley (now parts of India and Pakistan). These societies used measures for many tasks: trading for food, designing and sewing clothes, building dwellings or public buildings of an appropriate size and shape, or trading for raw materials. Our knowledge of early measuring methods comes from many sources. Some measuring devices, including early measuring standards, are still preserved in museums where they can be examined. Some buildings, such as the Egyptian pyramids, still exist and these can be measured directly. Another method is to compare the dimensions of old buildings with the writings of contemporary writers. For example, a fairly accurate idea of the size of the ancient Greek foot was obtained by measuring parts of the Greek Parthenon in Athens and comparing these measurements with a description of the Parthenon written by Plutarch (46/120). Then as now, the measures were arranged according to the quantity that was being measured. Generally they measured length, mass, volume, and time. Length Early measuring methods for length were based on the use of human body parts. Lengths and widths of fingers, thumbs, hands, hand spans, cubits, and body spans seem to have been popular choices. For example, early Babylonian and Egyptian records and the Bible indicate that length was first measured with the forearm (cubit ~ 500 mm), hand (width of male hand ~ 100 mm), or finger (one of three main fingers ~ 20 mm). The cubit was defined in these cultures as the length from the tip of a man's elbow to the end of his extended fingertips, and obviously this varies widely between different men. For modern men, a cubit can be quite close to 500 millimetres, so if a man puts the tips of his two long fingers together and places his forearms horizontally, his elbows will be quite close to 1 metre apart. The cubit was a commonly used measure in building construction. Mass (sometimes called weight) Body parts were not much use for measuring mass so various natural articles, that seemed to be reasonably consistent, were chosen to be the standards. Stones, grains of wheat or other small grains were a common choice. As examples, the word stones (of 6.350 kilograms) are still used to talk about body mass in the UK, and the carob seed became the basis of a measure called a carat (of 200 milligrams exactly) that is still used as a measure for gemstones. Uniform carob seeds must be hard to obtain as the carat has been defined as 200 milligrams for a long time.