Hi Jim, Much of the SI vocabulary is defined in the "International vocabulary of metrology - Basic and general concepts and associated terms (VIM)" - http://www.bipm.org/utils/common/documents/jcgm/JCGM_200_2012.pdf . You will notice that the vocabulary is in both English and French. It is my understanding that great even though English is the working language of the JCGM, trouble is taken to ensure that there is a one-to-one correspondence between English and French terminology - see the JCGM FAQ at http://www.bipm.org/utils/common/documents/jcgm/VIM_FAQs.pdf is also a source of further information.
Regards Martin -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of James Sent: 06 January 2014 17:10 To: U.S. Metric Association Subject: [USMA:53496] Re: Quantity in SI and 9th draft Dear Robert, In my view you are correct in that "quantity" implies "amount", but that is precisely what is meant here and elsewhere. We are speaking of things that can be measured; that is, they have "amounts" whether generally or specifically known. And those amounts (quantities) can be related by laws of physics and chemistry by means of mathematical formulae. Consider the electrical current flowing through a circuit. We call that quantity "electrical current" and often we wish to know the value for that amount of electrical current. That amount is then the quantity value. Sometimes we do not care to know the particular value for that quantity but it is still useful to speak of it generally. Thus, in Ohm's law, we do not speak of "25 amperes" but we speak of "electrical current". That current might have differing values in differing instances. To me, "property" differs from "quantity". Property describes an attribute such as whether a substance is fluid or solid, diamagnetic or paramagnetic, transparent or opaque, toxic or benign, lustrous or dull, etc. Yes, for many properties, such as these, there are indeed quantities that -- ahem -- quantify the extent of those properties. But that is not always the case. Consider the property of visual appeal. Only poets, painters, and sculptors can "quantify" beauty or ugly but those valuations are not universally repeatable. Jim On 2014-01-06 10:35, Robert H. Bushnell wrote: > 2014 Jan 6 > Dear Barry, > Thanks for posting the web address for the draft 9th SI. > > I have long been concerned about the use of the word quantity in SI. > To me quantity means amount. I think the public also thinks quantity > means amount, that is, how much. In the draft, including the history > part, I find no text saying why this word quantity is used. So, who > can tell me? > > I propose that quantity be deleted and the word property be used > instead. There might be another English word to use. > Somebody tell me what to use. > > Property is what units are about. > > "Property" is used throughout the text so this change is not easy but > let's do it. We have confused the public too long. > > Robert H. Bushnell PhD PE > member USMA > [email protected] > 502 Ord Drive > Boulder. CO 80303-4732 > 303-554-0728 > > > >
