Jim Elwell wrote:
....
> At 10:37 PM 21 June 2002 -0400, James R. Frysinger wrote:
> >...The SI depends extensively on what is called the quantity calculus ... it
> >boils down to viewing quantities as products of numbers and units and to
> >applying the rules of first year algebra to both parts.
>
> We certainly agree here. I want to make the point, however, that other than
> scientists and engineers, not only do people NOT understand "quantity
> calculus," they have very, very little need for it. In other words, 95% of
> the adult population of the world rarely if ever does any sort of
> "dimensional analysis" (as we called it when I was in school).
My point, which I obviously hid too well, was that all the quantity
calculus amounts to (at the common user level) is elementary algebra.
The ignorance of most people about elementary algebra, coupled with
their ignorance about dimensional analysis is a fact of life, but no
reason to "dumb down" the SI. Rather, we must patiently teach them
(rather than castigating them) on these matters. In fact, the SI lends
itself to making these concepts more clear than the hodgepodge of non-SI
units. Nothing in the name "knot" indicates that it is the ratio of
length to time. Nothing in "bushel" indicates that it is length cubed.
The diversity of energy units (Btu, calorie, quad, therm, ton, etc.)
make it seem that different forms of energy are somehow non-equivalent.
Similarly for the plethora of power units (hp, "BTU" [i.e., Btu/h], ton,
etc.).
> >...My guess is that all of the above led to the development of an
> >intentionally lean standard... Some might see its few rules as stifling,
> >claiming that their even simpler version causes no confusion. An example
> >of this might be the proposed omission of the unit after all but the last
> >product of numbers. Indeed, in that one field or even in several fields
> >there might be no possibility of confusion arising. But the SI is there to
> >cover all fields of measurement ... To allow some fields to simplify rules
> >of their choosing while others must adhere to those rules for the sake of
> >safety and clarity would be to make the SI no longer universal.
>
> Several comments: (1) correct me if I'm wrong, but neither the BIPM
> standard nor IEEE/ASTM SI 10-1997 address the example we've been using (1
> mm x 2 mm x 3 mm, vs. 1 x 2 x 3 mm). They DO, however, address putting a
> space between a number and its symbol, which I think is even less necessary
> for clarity.
I agree that the SI brochure does not provide such detailed comments
about writing out quantities. However, they obviously adhere to the
principles of the quantity calculus (oops, algebra of numbers and
units). One has only to read Metrologia or ISO standards to see how
metrologists deal with these matters. Of course, very few common users
*will* read Metrologia or ISO standards; for that matter, most people on
this list have no need to do so. Thus, they have a choice between
believing those who do or viewing this omisison in the brochure as carte
blanche to make up their own style. I submit that it is safer to go with
the standards that have made it through the consensus process of
development, critique, and approval. Or at least to trust those who are
familiar with those standards. But, as always, it's a matter of personal
choice whether to adopt this practice derived from formal procedures or
whether to adopt the "slang" of the streets.
> (2) For our example, some confusion may be due to technical people making
> something out of that which is not technical, illustrated by your statement
> "... omission of the unit after all but the last product of numbers."
>
> When we create a part description for a shipping box, and name it "box,
> shpng, 100x200x300mm" you see it as a "product of numbers." Non-technical
> people see it as three linear dimensions, and in no way related to being a
> product or volume. Perhaps we would all be more comfortable with:
>
> 100-200-300mm, or
> 100w200d300hmm, or
> 100/200/300mm
I don't see those as being sufficiently simpler than writing
100 mm x 200 mm x 300 mm
to inspire me to diverge from clear indications. How many picodollars or
milliseconds does your proposed style save you? And the space savings is
hardly stunning, in my opinion. If you need brevity, perhaps you could
say something like
"All dimensions given are in millimeters."
or
"Dimensions (mm): 100 x 200 x 300"
or
"Dim (mm): 100 x 200 x 300"
Something like the above is quite common in drawings, tables, and graphs
and those two examples are utterly clear.
> (3) Regardless of what you think of my examples above, I can say this:
> those of us in commerce have practical limitations that REQUIRE brevity in
> such things. As people knowledgeable about proper metric, us USMA types can
> either provide means for brevity, or people will develop them ad-hoc.
That's what the consensus process is for. Submit your proposals to the
owners of the standards that you use.
> I would welcome suggestions that address the brevity issue while keeping
> metric purists happy. And, no, mm^3 does not qualify: it is not understood
> by most people and writing a superscript 3 is nearly impossible in most
> accounting systems.
I think that education is the key. Once we do away with non-SI
measurements in this country, I expect to see a modicum of improvement
here. Our brandishment of non-standard SI usage certainly is not going
to help matters, but our usage of proper SI indications is at least
capapble of that.
....
> >You merely risk
> >demonstrating a departure from the rules that might be innocuous in your
> >field but perhaps harmful in others. And, of course, you are subject to
> >the pleasure and wrath of legally governing bodies who invoke those
> >rules and may show varying degrees of tolerance.
>
> Actually, I am subject to no such thing. Since my company does not sell
> consumer products, as far as I know there is no "legally governing body" in
> the US that has any authority over how we use measurements in our business,
> except if fraud is involved (e.g., calling a pound a kilogram).
So you're off the "retail" hook. Then, if the industrial customer and
you are happy that's all you have to worry about. In the US, that is. I
don't know how much other countries look into transactions not meant for
others than end users. Of course, if your industrial customer (or his
country) demands strict adherence to the SI, then your back is up
against a wall.
> I can even invent new units of measure if I wanted to -- perhaps a "nat"
> (as opposed to the common unit "nit") and call my displays "300 nat"
> displays when I really have not even defined "nat."
Sure. Goes good with "two scoops of raisins" and "makes clothes 20%
fresher smelling". People do it all the time. That's not very
standards-oriented, though.
> Of course, I would soon be out of business, thanks to the delightful forces
> of capitalism that punish such foolishness.
Yep. I suppose it's their fear that they might miss out on some VAT
revenue or such-like. Seems like a guy just can't sit around in his own
cave, gnawing on a joint of mastadon without someone from the government
wanting a piece of the meat.
....
> We're pretty much in agreement, except for (what started all this) some
> practical issues. I even agree that, with a few exceptions, it is easy to
> comply, and continue to wonder why I see so much "non compliance" in
> products from metric countries.
Same reason as in the US. Ignorance arising from poor education or lack
of desire to do things correctly (for one or more of thousands of
possible reasons).
> At 01:06 AM 22 June 2002 -0400, kilopascal wrote:
> >The people who run the media are part of the masses. They may not be
> >stupid, but they are ignorant and I'd bet non-caring of correct mathematical
> >and metric practices. And thus their errors are passed onto the masses who
> >follow the media. A never ending circle.
> >
> >The media should be made to realise that proper use of SI and its notations
> >are just as important as spelling and grammar.
Likewise when they look at indications on commercial packaging. If they
see that something they bought (perhaps with a QSI component embedded in
it) writes SI units out one particular way, they may assume that this
method is correct. Journalists publish newspapers and magazines. Highway
department officials publish roadsigns. You publish electrical boxes,
and influence your workers in the process.
....
> Our job is to get copies of these books (they generally will sell them),
> then point out where their style differs from international standards....
Hmmmm. Sounds familiar to my above comment, Jim. Ah, well, it's a free
country (sort of....). We usually get a chance to pick our battles.
Jim
--
Metric Methods(SM) "Don't be late to metricate!"
James R. Frysinger, LCAMS http://www.metricmethods.com/
10 Captiva Row e-mail: [EMAIL PROTECTED]
Charleston, SC 29407 phone/FAX: 843.225.6789
