Dear Joe, 'O frabjous day! Callooh! Callay! He chortled in his joy.'
I was unaware of these notes from South Africa. My preference for millimetres over centimetres is based solely on my experiences in agriculture, building, textiles, clothing, and footwear industries. I shall quote you, and this extract, widely and often I am absolutely delighted that you shared this with us. Best regards, Pat Naughtin CAMS Geelong, Australia on 2002-07-24 23.24, Joseph B. Reid at [EMAIL PROTECTED] wrote: > Pat Naugthin wrote in USMA 21372: > >> Please don't misunderstand me. I'm not suggesting that any official SI units >> (e.g. millilitres and millimetres) are technically inferior or superior to >> any other units (e.g. centilitres and centimetres). What I am saying - as >> strongly as I can - is that for any nation that is currently in the process >> of metrication, the choice of millimetres and millilitres will hasten the >> process remarkably. >> >> I used to say that you could teach a builder's laborer enough SI units to >> construct a house in 50 minutes - using millimetres; and it takes at least >> 50 years to teach a clothing worker enough SI units to construct a skirt - >> using centimetres, and I only had my tongue slightly in my cheek. > >> If you choose >> centimetres as the small unit of length for metrication at your place of >> work, you should also settle down for the 50 year wait for the conversion >> process to be complete. > >> Pat Naughtin CAMS > > > South African Metrication News, 1978-07/08 wrote: > 1. One of the most important aims of the SI is the simplification and > rationaliation of units, both for measurment and for use in calculations. > The number of multiples and sub-multiples is accordingly restricted by > giving preference to the use of prefixes that represent steps of 1 000 (x > 10^3) > 2. If this preferred range of prefixes is combined with the division of > numerals into groups of three then this makes for extreme ease of > converssion from, say mm to m by simply moving the decimal indicator to the > next aoolicable space viz: > 1 725 352 mm = 1 725,352 m = 1,725 352 km > 3. If the centimetre is interposed between the millimetre and the metre > it has several disadvantages: > (i) It destroys the simplicity of the system, > (ii) It makes it impossible to use the *groups of three* method to > change from centimetres, say, as the gap is in the wrong place viz: > 76 322 cm = 763,22 m > But there will be a tendency - using the *gap* theory - to make the answer > 76,322 m (a tenfold error). > (iii) It is universal practice in technical drawings to use > millimetres only. If this practice is employed all that has to be done is > to write *all dimensions in millimetres* at the top of the drawing and then > leave all symbols off each dimension - a tremendous saving of time and > ensuring that errors in transcription are avoided. > If centimetres are permitted as well as millimetres then it would be > necessary to use symbols again after every dimension and the risk of error > in transcription is very great indeed. > 4. It should be noted that the objection to centimetre is confined to > its use as a linear measure. When raised to the second and third powers, as > in areas and volumes respectively, it is necessary to employ square > centimetres and cubic centimetres to render the steps betweeen successive > multiples of area and volume, practical ones. > 5. In South Africa the centimetre is used in the clothing and textile > industries and therefore also for related dimensions of the the human body. > It should, preferably, not be introduced elsewhere. > 6. If the centimetre were given equal status with the millimetre we > would have the situation where some people would specify the dimensions of, > say, a piece of paper in centimetres and others would specify its > dimensions in millimetres. This would be very confusing and would defeat > one of the main objects of introducing a univeersal language of > measurement. > 7. There is no doubt that the preference that many people have for the > centimetre is merely aother throw-back to the imperial system - it is the > sub-multiple of the metre that is most closely relatred to the inch - and > such people naturally tend to use it in all applications where the inch was > previojsly used. This "cross-section" of people is, however a dimnishing > one. > 9. The SI, if it is to retain its simplicity and its coherency, must > employ as few sub-multiples and multiples as possible. Nobody wishes to > interpose centigram between milligram and gram, for example, nor > centinewton between millinewton and newton, nor centivolt between millivolt > and volt, etc., and basically there is no reason why the measurement of > length should require special treatment when it has been proven to be > unnecessary for mass, force, electrical potential, etc. > > Joseph B.Reid > 17 Glebe Road West > Toronto M5P 1C8 Tel. 416 486-6071 >
