|There are NO units of currency.|
|There is an outline of the||S I system,|
|a list of its 7 basic||definitions,|
|some of its||derived units,|
|together with a list of all the||S I prefixes,|
|and some of the rules and conventions for||its usage.|
|On the subject of measures generally, there is a short||historical note.|
|Then there are descriptions of the||Metric system,|
|and the||U K (Imperial) system,|
|followed by statements on the implementation of||'metrication' in the U K,|
|and then the||U S system of measures.|
|At the bottom of this document is a||list of other sources,|
|and also some links to other||Web sites.|
|And then there is its||publishing history .|
|There is a separate document covering the most||FAQ and other measures.|
Category Name Abbrev. Length metre m Mass kilogram kg Time second s Electric current ampere A Temperature kelvin K Amount of substance mole mol Luminous intensity candela cd
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The Prefixes of the S I
The S I allows the sizes of units to be made bigger or smaller by the use of appropriate prefixes. For example, the electrical unit of a watt is not a big unit even in terms of ordinary household use, so it is generally used in terms of 1000 watts at a time. The prefix for 1000 is kilo so we use kilowatts[kW] as our unit of measurement. For makers of electricity, or bigger users such as industry, it is common to use megawatts[MW] or even gigawatts[GW]. The full range of prefixes with their [symbols or abbreviations] and their multiplying factors which are also given in other forms is
yotta [Y] 1 000 000 000 000 000 000 000 000 = 10^24
zetta [Z] 1 000 000 000 000 000 000 000 = 10^21
exa [E] 1 000 000 000 000 000 000 = 10^18
peta [P] 1 000 000 000 000 000 = 10^15
tera [T] 1 000 000 000 000 = 10^12
giga [G] 1 000 000 000 (a thousand millions = a billion)
mega [M] 1 000 000 (a million)
kilo [k] 1 000 (a thousand)
hecto [h] 100 (a hundred)
deca [da]10 (ten)
deci [d] 0.1 (a tenth)
centi [c] 0.01 (a hundredth)
milli [m] 0.001 (a thousandth)
micro [µ] 0.000 001 (a millionth)
nano [n] 0.000 000 001 (a thousand millionth)
pico [p] 0.000 000 000 001 = 10^-12
femto [f] 0.000 000 000 000 001 = 10^-15
atto [a] 0.000 000 000 000 000 001 = 10^-18
zepto [z] 0.000 000 000 000 000 000 001 = 10^-21
yocto [y] 0.000 000 000 000 000 000 000 001 = 10^-24
Nearly all of the S I prefixes are multiples (kilo to yotta) or sub-multiples (milli to yocto) of 1000. However, these are inconvenient for many purposes and so hecto, deca, deci, and centi are also used.
deca also appears as deka [da] or [dk] in the USA and Contintental Europe. So much for standards!
OR Notes on Prefixes (inc. other types)
One of the earliest types of measurement concerned that of length. These measurements were usually based on parts of the body. A well documented example (the first) is the Egyptian cubit which was derived from the length of the arm from the elbow to the outstretched finger tips. By 2500 BC this had been standardised in a royal master cubit made of black marble (about 52 cm). This cubit was divided into 28 digits (roughly a finger width) which could be further divided into fractional parts, the smallest of these being only just over a millimetre.|
In England units of measurement were not properly standardised until the 13th century, though variations (and abuses) continued until long after that. For example, there were three different gallons (ale, wine and corn) up until 1824 when the gallon was standardised.
In the U S A the system of weights and measured first adopted was that of the English, though a few differences came in when decisions were made at the time of standardisation in 1836. For instance, the wine-gallon of 231 cubic inches was used instead of the English one (as defined in 1824) of about 277 cubic inches. The U S A also took as their standard of dry measure the old Winchester bushel of 2150.42 cubic inches, which gave a dry gallon of nearly 269 cubic inches.
Even as late as the middle of the 20th century there were some differences in UK and US measures which were nominally the same. The UK inch measured 2.53998 cm while the US inch was 2.540005 cm. Both were standardised at 2.54 cm in July 1959, though the U S continued to use 'their' value for several years in land surveying work - this too is slowly being metricated.
In France the metric system officially started in June 1799 with the declared intent of being 'For all people, for all time'. The unit of length was the metre which was defined as being one ten-millionth part of a quarter of the earth's circumference. The production of this standard required a very careful survey to be done which took several years. However, as more accurate instruments became available so the 'exactness' of the standard was called into question. Later efforts were directed at finding some absolute standard based on an observable physical phenomenon. Over two centuries this developed into the S I. So maybe their original slogan was more correct than anyone could have foreseen then.
Length Area 10 millimetres = 1 centimetre 100 sq. mm = 1 sq. cm 10 centimetres = 1 decimeter 10 000 sq. cm = 1 sq. metre 10 decimetres = 1 metre 100 sq. metres = 1 are 10 metres = 1 decametre 100 ares = 1 hectare 10 decametres = 1 hectometre 10 000 sq. metres = 1 hectare 10 hectometres = 1 kilometre 100 hectares = 1 sq. kilometre 1000 metres = 1 kilometre 1 000 000 sq. metres = 1 sq. kilometre Volume Capacity 1000 cu. mm = 1 cu. cm 10 millilitres = 1 centilitre 1000 cu. cm = 1 cu. decimetre 10 centilitree = 1 decilitre 1000 cu. dm = 1 cu. metre 10 decilitres = 1 litre 1 million cu. cm = 1 cu. metre 1000 litres = 1 cu. metre Mass 1000 grams = 1 kilogram 1000 kilograms = 1 tonne
Length Area 12 inches = 1 foot 144 sq. inches = 1 square foot 3 feet = 1 yard 9 sq. feet = 1 square yard 22 yards = 1 chain 4840 sq. yards = 1 acre 10 chains = 1 furlong 640 acres = 1 square mile 8 furlongs = 1 mile 5280 feet = 1 mile 1760 yards = 1 mile Capacity 20 fluid ounces = 1 pint Volume 4 gills = 1 pint 1728 cu. inches = 1 cubic foot 2 pints = 1 quart 27 cu. feet = 1 cubic yard 4 quarts = 1 gallon (8 pints) Mass (Avoirdupois) 437.5 grains = 1 ounce Troy Weights 16 ounces = 1 pound (7000 grains) 24 grains = 1 pennyweight 14 pounds = 1 stone 20 pennyweights = 1 ounce (480 grains) 8 stones = 1 hundredweight [cwt] 12 ounces = 1 pound (5760 grains) 20 cwt = 1 ton (2240 pounds) Apothecaries' Measures Apothecaries' Weights 20 minims = 1 fl.scruple 20 grains = 1 scruple 3 fl.scruples = 1 fl.drachm 3 scruples = 1 drachm 8 fl.drachms = 1 fl.ounce 8 drachms = 1 ounce (480 grains) 20 fl.ounces = 1 pint 12 ounces = 1 pound (5760 grains)
1 yard = 0.9144 metres - same in US|
1 pound = 0.453 592 37 kilograms - same in US
1 gallon = 4.546 09 litres - different in US
There have been three major Weights and Measures Acts in recent times (1963, 1976 and 1985) all gradually abolishing various units, as well re-defining the standards. All the Apothecaries' measures are now gone, and of the Troy measures, only the ounce remains. The legislation decreed that -
From the 1st October 1995, for economic, public health, public safety and administrative purposes, only metric units were to be allowed EXCEPT that -
The following could continue to be used WITHOUT time limit -
That was how the legislation was framed. In common usage the 'old' units are still very apparent.
|Historical Perspectives on Metrication by Jim Humble|
who was the last Director of the UK Metrication Board.
The first parliamentary reference to metrication in the UK was 13th April 1790. This was when parliamentarian Sir John Riggs Miller [Britain] and the Bishop of Autum, Prince Talleyrand [France] put to the British Parliament and French Assembly respectively, the proposition that the two countries should cooperate to equalise their weights and measures, by the joint introduction of the metric system.
There was no immediate progress although there were many positive debates in the second half of the 19th Century. For example, 1st July 1863 the Bill for a compulsory change to the metric system was approved by 110 votes to 75 votes. Speakers argued many of the points we hear today. On the one hand supporters argued its logic and simplicity, savings in time and money, advantages to trade and education. Opponents stressed the undesirability of following the precedent of France and the problems of conversion for the illeducated and disadvantaged. However no specific cut-off dates were proposed.
The following year, 9th March 1864, the House of Lords debated a Bill to permit the use of metric weights and measures in trade. One supporter noted that Englishmen were notorious for liking old terms and old habits and he hoped that the new nomenclature would not be diverted by attempts at ridicule. He said the sound of the word 'metric' can be absurd to anyone but a fool who has never heard it before; but no more than a 'yard' to a man who has never heard of a 'yard' before.... !!! Parliament passed the Bill and this became the Metric Weights and Measures Act 1864.
On the 24th February 1868 a parliamentary proposal to set Imperial cut-off dates was withdrawn on promise of a Royal Commission of enquiry. The Enquiry Report was positive, and on the 26th July 1871 Britain almost became a metric country. The government lost the Bill to make metric compulsory after two years, by only 82 votes to 77 votes. An argument that might have influenced opponents was a plea that Britain would be "letting down America and our colonies" who had harmonised their systems with the ones in use in Britain. [NB At that time the American Congress had emulated Britain by allowing contracts in metric. A particularly strong USA advocate for metric was John Quincy Adams.]
There were further debates, and near misses, in the UK Parliament in 1872 and 1896, before a comprehensive debate [21st June - 6th August 1897] concluded by legalising the use of metric for all purposes. There were no contrary votes. [NB This is the debate which most references indicate to be the genesis of metrication in the United Kingdom.]
Metrication continued to be debated for the next 10 years. In 1904 The House of Lords unanimously voted to make metric compulsory after two years. It was claimed that the Austrian and German nations had successfully made metric compulsory with a changeover time of only "one week"!!!!! . The Government said they would not obstruct the proposal, but the Bill was never adopted in the Commons. Two similar debates in 1907 failed. By now, the Board of Trade was expressing some reservations, claiming that metrication had failed in France and that the agricultural labourer would never ask for 0.56825 of a litre of beer. The vote against compulsion rose to 150 votes to 118 votes. Conflicts in Europe put further political consideration of metrication out of mind until the publication of a Government White Paper on Weights and Measures 10th May 1951.
The 1951 White Paper was in fact the 28th Report put to Parliament during the preceeding 100 years. This latest report was in response to the the Hodgson Committee Report published in 1949. Eventually we had the Weights and Measures Act 1963; a long series of Parliamentary questions to Ministers and the Federation of British Industries [now the CBI] lobby in favour of metrication in 1965. These initiatives culminated with the creation of the Metrication Board in 1969 by Anthony Wedgewood Benn, Minister of Technology. The target date for completion was end 1975. The transition to metrication and the role of the Board were given positive support and encouragement by Geoffrey Howe the responsible Minister of the new Government in 1972. Indeed at that time, and until circa 1977/8, there was good, sensible and steady progress which seemed to be supported by every section of society including, for example, the small retailers and the elderly as represented by Age Concern.
Prepackaged food changed but the really difficult issue to emerge affected retailers of 'loose weight' products. They needed to be reassured there would be an agreed cut-off date for their transfer from Imperial to metric. The retail problem was that metric prices would always appear to be more expensive than their nearest Imperial equivalent. Voluntary transferees to metric found themselves commercially disadvantaged. This is because viz. 4 ozs is smaller than 125 g: one pound is smaller than 500 g and a pint is smaller than a litre. Prices are correspondingly lower. The issue of how best to explain the position to consumers dominated much of the Board's creative thinking.
The product which brought all voluntary retail initiatives to a full stop was the experience of the floor covering and carpet retailers. Their 1975 change to sales by the sq. metre started well, but in 1977 one of the major High Street retailers found enormous commercial advantage in reverting to sales by the square yard. Consumers could not be persuaded to believe that goods costing, for example, £10 per square yard or £12 per square metre were virtually priced the same. Consumers bought, in very significant volume, the apparently cheaper priced imperial version. Metrication of carpet sales entered into full scale reverse and the Chambers of Trade and retail associations pressed for firm Government leadership i.e. compulsory cut-off. With hindsight one of the Metrication Board jingles may have helped spread the 'carpet' misunderstanding. This was the jingle " a metre measures about three foot three, just a bit longer than a yard you see". Consumers understandably couldn't relate an e.g. £2 per square unit price difference with the Metrication Board's "just a bit longer". Then the political nerve began to fail.
Board of Trade Ministers Shirley Williams, Alan Williams and later Roy Hattersley and John Fraser supported metrication. They seemed to recognise the setting of a cut-off date was unavoidable. They had had, by this time, the benefit of analysing the results of successful metric changes in all the Commonwealth countries. There was a wealth of information within the Department of Trade to show that a clear retail cut-off date was both desirable and inevitable....exactly as 19th Century parliamentarians had forseen. The necessary Order, drafted by the Board of Trade in 1978, was agreed by a huge range of retail trade, industry, engineering, consumer, trade union, elderly person, sporting and educational organisations and..... the overwhelming number of parliamentarians. A small number of critics, in each political party, did voice opposition to the element of compulsion but this seemed to come from a relatively small minority within the Eurosceptic movement.
However, the initiative was in the hands of Secretary of State for Trade, Roy Hattersley and a General Election was expected in 1979. There seemed to be weeks and weeks of "will he/ won't he" allow Parliament to vote for the Order giving the final Imperial cut-off. Almost every private test of opinion indicated the Order would command a substantial majority in Parliament. Although the Opposition sensed a weakness in the resolution of the Labour Government it was acknowledged that many conservative MPs had been career-long advocates for cut-off and would therefore be likely to favour the Government Order, or at least abstain. In the event, Roy Hattersley chose not to test opinion, not to allow the vote. He withdrew the draft Order. Speculation was that he judged the issue might lose some votes in the forthcoming election. Plenty of time to introduce Imperial cut-off Orders after a Labour victory. The junior Trade Minister, John Fraser, made his disgust and disappointment apparent... suggesting the actions of his Secretary of State would be seen as "gutless". Many shared that view. Labour lost the election anyway and Margaret Thatcher became Prime Minister.
One Conservative backbencher, Sally Oppenheim had been almost the lone but persistent critic of the metric programme. Ironically she was appointed junior Minister of Consumer Affairs at the DTI and then metrication was added to her portfolio. In letters to MP's and associations she made it clear
[a] she was not opposed the metrication in principle,
[b] metrication was not the result of Britain's accession to the EEC but
[c] she did object to measures which would compel people to adopt metric against their will. Proponents of metrication, trade and consumer organisations, officials and the Metrication Board explained and argued that a voluntary change at retail level was absolutely impossible...it could never happen. It was a recipe for confusion, waste and duplication. Government had to lead over the last hurdle. It did, it led backwards. In 1980 the Metrication Board was abolished.
In truth the Metrication Board had little else to do. Every possible programme had been agreed, consumer information campaigns composed and there was nothing to do until or unless a date was fixed for the completion of the transition. We little knew then the die was set for a further 20 years of waste, confusion and argument. Successive DTI Ministers did nothing to inform consumers or public opinion. They did nothing to refute the new 'big lie' namely, that Britain was being forced to change because of the European Commission. In fact, during the past 20 years most Commission Officials, European Politicians and businesses in Continental Europe 'couldn't have given a damn' whether Britain changed to the metric system or not. They seemed to quite like the idea of Britain shooting itself in its economic foot, by imposing upon itself the extra costs and waste of maintaining a dual system. For twenty years not one single British Minister has attempted to explain the advantages of metrication; been frank about the changes which had successfully taken place in the rest of the World or the fact that we had committed ourselves to become a metric nation long before we joined the European Community. Most tried to pretend or imply they were protecting our British culture from the European bully.
How sad, what a waste, what a pity.
Jim Humble OBE
Director of the Metrication Board
Some other dates of note|
1950 The Hodgson Report
was published which, after arguing all the points for and against, favoured a change to metric.
1963 Weights and Measures Act
defined the basic measures of the 'yard' and the 'pound' in terms of the 'metre' and the 'kilogram'. Many of the old imperial measures were abolished (drachm, scruple, minim, chaldron, quarter, rod, pole, perch, and a few more)
1971 Currency was Decimalised
1985 Weights and Measures Act
abolished several more imperial measures for purposes of trade, and defined the 'gallon' in terms of the 'litre'.
Thus, all the measures had been metricated even if the public hadn't!
Length Area 12 inches = 1 foot 144 sq. inches = 1 square foot 3 feet = 1 yard 9 sq. feet = 1 square yard 220 yards = 1 furlong 4840 sq. yards = 1 acre 8 furlongs = 1 mile 640 acres = 1 square mile 5280 feet = 1 mile 1 sq.mile = 1 section 1760 yards = 1 mile 36 sections = 1 township Volume 1728 cu. inches = 1 cubic foot 27 cu. feet = 1 cubic yard Capacity (Dry) Capacity (Liquid) 16 fluid ounces = 1 pint 2 pints = 1 quart 4 gills = 1 pint 8 quarts = 1 peck 2 pints = 1 quart 4 pecks = 1 bushel 4 quarts = 1 gallon (8 pints) Mass 437.5 grains = 1 ounce Troy Weights 16 ounces = 1 pound (7000 grains) 24 grains = 1 pennyweight 14 pounds = 1 stone 20 pennyweights = 1 ounce (480 grains) 100 pounds = 1 hundredweight [cwt] 12 ounces = 1 pound (5760 grains) 20 cwt = 1 ton (2000 pounds) Apothecaries' Measures Apothecaries' Weights 60 minims = 1 fl.dram 20 grains = 1 scruple 8 fl.drams = 1 fl.ounce 3 scruples = 1 dram 16 fl.ounces = 1 pint 8 drams = 1 ounce (480 grains) 12 ounces = 1 pound (5760 grains)
1 yard = 0.9144 metres - same as UK|
1 pound = 0.453 592 37 kilograms - same as UK
1 gallon (liquid) = 3.785 411 784 litres
1 bushel = 35.239 070 166 88 litres
Conversion Tables of Units for Science and Engineering
The Dent Dictionary of Measurement
The Economist Desk Companion
The Encyclopaedia Britannica
World Weights and Measures
|The Weights and Measures of England|
by R D Connor
H M S O, London, 1987 (422 pages)
ISBN 0 460 86137 9
A scholarly and detailed account of the history of the development of the British (Imperial) system of weights and measures from the earliest times.
British Weights and Measures
The World of Measurements
Scientific Unit Conversion
The first to be considered must the Official SI Web-site in France.
In the UK a very good place to make a start is the UK Metric Association. It covers just about everything one could want to know about metrication and, if not covered, gives links to sites where you might find it. Current state of progress, legislation, directives, arguments (for and against), conversions, practical usage and many other points of interest, all get a mention.
In the USA the National Institute of Standards and Technology (NIST) is excellent, and there is no shortage of information concerning units and their conversion. There is even an excellent 86-page book on the subject (SP 811) which can be read on-line or downloaded and printed out.
An excellent A to Z of units is available from this site run by Russ Rowlett at the University of North Carolina.
Another account of metrication and associated items which has, in addition, some very good pages on historic measures (Anglo-Saxon, Biblical etc.) is provided by Jack Proot (in Canada)
The International Standards Organisation] [I S O] based in Switzerland, is responsible for the world-wide publication of standards for just about anything for which standards can be set. Whilst none of the actual data is online, details of the work of ISO and the publications they produce are. They also give many references to other organisations concerned with standards.
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