[USMA:36664] RE: Kiloliters

[Bill Hooper]

On 2006 Apr 26 , at 1:28 PM, Stephen Gallagher wrote: But I'd rather hear that a bucket contains 6 L of water and not 0.06 cubic meters of water.   But 6 L equals 0.006 cubic metres! However, I'll assume that that was a minor arithmetic or typographical error and I should like to concentrate on a different aspect of it. Assuming that Stephen meant to write: But I'd rather hear that a bucket contains 6 L of water and not 0.006 cubic meters of water. I would respond with ... Granted! And it's also better to use 6 L than 6000 cm^3. That's what the litre was created for ... to bridge the rather large range between the cubic centimetre and the cubic metre (or the even more difficult range between a cubic millilmetre and a cubic metre). But how about 249 000 litres? ... or 0.0175 litres? Wouldn't you agree that they are easier to use if  the 249 000 litres is expressed as 249 m^3  and the 0.0175 litres is expressed 17.5 cm^3 ? I think that's where I would argue that we should not use litres because the litre is not a convenient size for those measurements. I further contend that it is also better not to use kilolitres or millilitres. The reason is that a kilolitre is just a cubic metre so why not use cubic metres, and the millilitre is just a cubic centimetre so why not use cubic centimetres. (See also PS at end.) The principle is to prefer have only ONE unit not several for the same thing. Instead of allowing kilolitres AND cubic metres, it is preferable to use the SI unit, the cubic metre and never the kilolitre. Similarly with cubic centimetres vs. millilitres.  However, where the cubic metres is too large and the cubic centimetre is too small, the litre should be used even if it is not an SI unit. (It is, however, officially acceptable for use WITH the SI.) Since the litre is not an SI unit, it is not appropriate (within SI) to add the SI prefixes to it to get kilolitres or millilitres. Regards, Bill Hooper Fernandina Beach, Florida, USA PS My references to the cubic centimetre above would have to be re-thought if I should follow Pat Naughtin's suggestion that we should use ONLY millimetres and never centimetres (cubed or otherwise), a proposal which I find attractive although I have not yet been completely converted.  If the cenitmetre is to be abandoned, then the millilitre would be just as important as the litre for bridging the large gap between the two SI volume units (m^3 and mm^3). That would lead to the set of relationships below, which is not too bad: 1000 mm^3 = 1 mL 1000 mL = 1 L 1000 L = 1 m^3 ==========================    Make It Simple; Make It Metric! ==========================