On Fri, May 23, 2008 at 5:52 AM, Ian Lynch <[EMAIL PROTECTED]> wrote:
> But we do have 1 cubic cm of water weighing 1 gram. 1 cubic metre of > water weight one metric tonne or 100 kgs. That is pretty neat. > > Okay. So let's make up a new system for a moment. Start with a unit of length, call it a "stick" and set it equal to 1 decimeter. Now define a unit of mass, call it a "rock", and define it as the mass of 1 cubic stick of pure water. You will notice that a cubic stick is what we now call a liter and a rock is equal to a 1 kg. I think my sticks and rocks are more neatly related than your meters and kilograms. > > That way the basic units, sans prefixes, would have been a bit more more > > "human-scaled". > > That depends on the industry you work in. People work on things from > very small to very big. A person is generally about 2m tall so a metre > in every day life is a pretty sensible size. It's very close to a yard > which is a common imperial base unit. The kg is the same order of > magnitude as a lb and the second is common to both systems. A yard is fairly common Imp unit but have you ever heard someone described as 2 yards tall? Six feet, yes, and even 72 inches occasionally, but never 2 yards. My stick would be very nearly 4 inches, which I believe is equal to a hand. It may be a holdover from Imperial, but in conversation "1 and a half" and "2 and three-quarters" sounds more natural. At 6 ft 3 in, I would be 19 sticks high. Why is that better than 1.9 meters? Maybe it's just me, but unless I'm in a scientific or technical context I tire of using the word point all the time. We just don't do it in ordinary conversation much. The order of magnitude of the kg is fine, but a fundamental unit shouldn't use a prefix as noted by Mr. Kennedy. > > > > I realize it's all a bit arbitrary in the end, but I find it > > less than ideal that the units that are used most often in ordinary usage > > all seem to require prefixes. A human weight is best measured in > KILOgrams, > > a human height in CENTImeters, etc. > > Human height could well be 1.67m Compare that to 5 foot 8 1/2ins or > 681/2 ins. Try dividing each by 3. I don't think you can argue on the > base sizes and prefixes since at least there is a pattern to the metric > pre-fixes, there is no pattern from inch, foot, yard, furlong, mile etc. > The words give no clue as to the relationship between each whereas I > know centi is always a hundredth and kilo means a thousand. Its then > simply a matter of moving a decimal point. Rather a lot easier than the > more complex arithmetic caused by mixing different number systems into > the units of measure. Decimal units -- fine. Common prefix system -- wonderful. Different measurement units logically related to each other -- fantastic. My problem isn't with the concept. My only gripe (and it's a minor one just cuz we're talking among friends here) is with the execution. > > > > Does any of that make sense or have I been up too late again? > > Probably :-) > Rod
