That and the standard tolerances are normally given in the notes to avoid hundreds of restatements.
--- On Fri, 3/13/09, Jeremiah MacGregor <[email protected]> wrote: > From: Jeremiah MacGregor <[email protected]> > Subject: [USMA:43769] Re: Fw: Re: Metric personal data was Re: 24 hour time > To: "U.S. Metric Association" <[email protected]> > Date: Friday, March 13, 2009, 10:23 PM > Naked numbers are common on drawings when the units are > understood. There may be a note somewhere that may read: > All units in mm unless otherwise stated. > > Jerry > > > > > ________________________________ > From: John M. Steele <[email protected]> > To: U.S. Metric Association <[email protected]> > Sent: Thursday, March 12, 2009 9:01:18 AM > Subject: [USMA:43708] Re: Fw: Re: Metric personal data was > Re: 24 hour time > > > > None of the choices, 1.81 m, 181 cm, or 1810 mm, are > wrong. Perhaps one is preferred and the other two are > acceptable (if only we could agree on which). Europe, in > particular, uses the centimeter in clothing sizes and I > doubt you will talk them out of it. > > I'd like to comment on a couple of your other points > to. The liter is not exactly an SI unit, but permitted for > use with it. The centiliter is commonly used in Europe. > The wine bottle we label 750 mL is labelled 75 cL there. I > assume this is a matter of law. They require it, we forbid > it. > > Your examples of numbers over 1000 are all quite rounded. > In the spoken word 3000 miles becomes three thousan miles. > "Thousand miles" becomes a new pseudo-unit and > with nothing following it, in some respects, it is no longer > a large number (your one counterexample becomes fifteen > hundred gallons, same thing). 1810 mm does not work out so > well. > > > Back to the original example, none of the three forms is > really a problem as long as the units stay attached to the > number. The big problem occurs when the units are not > explicitly stated, what I call "naked numbers." > Naked numbers are VERY confusing unless there is a > well-known norm for the units. It may be wise to establish > a norm for that reason. Since the rest of the world is > more metric than us, the first place to look might be how > they do it, since we don't have a well-established > precedent of our own (we do have a well-established > precedent in spelling differences, I don't propose > changing that, but why INVENT new differences) > > I waffle on whether meters or centimeters is the better > choice, but I think millimeters has the weakest argument. > > --- On Wed, 3/11/09, Bill Hooper > <[email protected]> wrote: > > > From: Bill Hooper <[email protected]> > > Subject: [USMA:43700] Re: Fw: Re: Metric personal data > was Re: 24 hour time > > To: "U.S. Metric Association" > <[email protected]> > > Date: Wednesday, March 11, 2009, 10:09 PM > > On Mar 11 , at 4:48 PM, John Frewen-Lord wrote: > > > There I suggest using cm (sorry Pat N), as people > can > > then express their height verbally as, say, One > Seventy > > Eight - which can be interpreted by the listener as > either > > 178 cm or 1.78 m - both are the same value. > > > > > > John says you can say "one seventy-eight" > and in > > can easily be understood to mean 1.78 m or 178 cm. > However, > > you can also say "one, seven-eighty" which > can be > > easily interpreted as 1.780 m or 1780 mm (which are > also the > > same value). That argument fails in showing that > centimetres > > are better than millimetres for this measurement. > > > > It really is NOT easier one way or the other. Some > things > > seem easier just because we're more familiar with > them. > > > > Virtually all other prefixes in SI are multiples of > 1000. > > The centimetre is the ONLY commonly used SI unit that > uses > > the prefix "centi". (Emphasis on > > "common".) As such, it is reasonable to > suggest > > that we drop it so we have one less prefix to bother > with. > > > > Yes, I know that the centimetre is still an official > part > > of SI, but if it is unnecessary, we don't have to > use > > it. SI tells us what we MAY use in SI; it does not > tell us > > that we MUST use an particular part of it. > > > > It seems funny to me, too, to report my height in > > millimetres. I first learned my height in metric on a > > centimetre measuring rod. So I learned 181 cm and I > became > > familiar with that. I often find it convenient to > refer to > > it my height as 1.81 m but I know some people are > > uncomfortable using fraction ("Why", > I'll > > never know!) and, therefore, they feel more > comfortable with > > 181 cm. But there really is nothing wrong, difficult > or > > awkward about using 1810 mm. > > > > I would agree that it would probably need to be > understood > > that such measurements are good only to the nearest 10 > mm, > > that is, the trailing zero is usually not a > significant > > figure. However, there are plenty of example in daily > life > > where we use numbers that large and we might have > problems > > understanding the implied precision, and they seem to > give > > us no trouble. Some examples (in our comfortable Olde > > English units) are: > > > > The distance from New York to San Francisco is > about > > 3000 miles. > > Last year I earned $75,000. (I didn't, by the > way!) > > The Dow John Average has fallen over 7000 points > since > > it's highest value. > > Mt. Everest is 29,000 feet high. > > I paid $113,000 for that house. > > The distance to the moon is 239,000 miles. > > I use about 1500 gallons of gas a year in my car. > > The NFL season rushing record is over 2000 yards. > > I have only about 17000 frequent flyer miles. > > The speed of sound is a little over 1000 ft/s. > > > > If we're not turned off by these and hundreds of > other > > example with numbers over 1000, then why are we > bothered by > > my height stated as 1819 mm? > > (That previous sentence is NOT merely a rhetorical > > question; we ARE bothered and I'm asking if you > know > > why. Do you know?) > > > > > > Bill Hooper > > 1810 mm tall > > Fernandina Beach, Florida, USA > > > > ========================== > > SImplification Begins With SI. > > ==========================
