>No, that's not the main advantage of the litre. The main (only?) >advantage to the litre is that it is a convenient size for ordinary household uses,
I will concede 'main' but not 'only' as I still maintain that the familiar relationship between ml, cl & L to be a useful feature. >But I am not recommending that we now* stop using millilitres or >centilitres (how about decilitres?), since they are to a greater or >less greater extent already in common use. I am recommending that we >NOT introduce kilolitres and megalitres etc, because they are NOT >already in common use (and they certainly are not needed for common >household uses). The reason that some prefixes are common and others are not is simply that some correspond to useful sizes and others do not. That is why we have centimeters, but not centigrams, decibels but not deciliters. You don't have to legislate on this; the prefixes are there to make it convenient. The important thing is that people are educated to know what milli, centi-, deci- etc mean so that will know what a unit is when they see if for the first time (and why trying to remove centi- & deci- from SI education is a BAD idea). >You can't imagine a shopper asking for a gigalitre of milk, can you? I can't imagine a trucker stating his load in megagrams either, although this would be more orthodox SI than stating it in tonnes. People will use the units that are convenient, not what are 'pure'. >But if an oil company wants to buy a gigalitre of oil, they can jolly >well call it a million cubic metres (1 000 000 m^3). >And if they don't like all writing all those zeros, I'm sure their engineers >and their business people are sufficiently well educated to be able to write >it in scientific notation (power of ten notation). But why should they have to ? GL would seem to be a useful unit to use for that large quantity. Why should they be forced to choose between lots of zeroes and scientific notation (which I'm perfectly happy with as a scientist, but this also has the unfortunate effect of reinforcing the metric-is-only- for-scientist prejudice). SI is supposed to be about making measurement easier. Why make it more awkward by denying access to useful units ? >* I think it might be wise ultimately to try to rid ourselves of the >millilitre and centilitre (and decilitre), but I am not advocating that >we try to do it right now. But WHY rid ourselves of it at all ? If people find it convenient to use, why try to make things awkward for them ? Let's not try to shoehorn use of metric into a small subset of the available choice of prefixes and units just to satisfy a purist interest, or a prejudice against prefixes that aren't a power of 1000. ------------------------------------------------------------------- Tom Wade | EMail: [EMAIL PROTECTED] EuroKom | X400: g=tom;s=wade;o=eurokom;p=eurokom; Unit A2 | a=eirmail400;c=ie Nutgrove Office Park | Tel: +353 (1) 296-9696 Rathfarnham | Fax: +353 (1) 296-9697 Dublin 14 | Disclaimer: This is not a disclaimer Ireland | Tip: "Friends don't let friends do Unix !"
