2002 September 5
In 22080 Louis Jourdan gives an important reference to the BIPM/ISO
vocabulary wherein "quantity" is used in the meaning that
mass is a quantity
length is a quantity
time is a quantity
temperature is a quantity
etc.
I object to this use of the word "quantity" in this sense. The word we
should use in English is "property". In French "grandeur" has the same
problem which is that "quantity" means "how much" (amount) to the public.
It does not mean "kind" as used by deBoer and ISO.
Notice in 22080 1.1 we see "quantity" may be determined "quantitatively".
This has two meanings in one sentence.
Notice 1.7 unit: a quantity with which other quantities are compared.
This is hopeless. Some of the other quantities are listed above. Is
time ever compared with mass? They try to be clear by saying, not
just "quantities", but "quantities of the same kind". This helps a
little but better yet try
1.7 Unit (of measurement). A particular amount, the unit, of
a property with which other amounts of the same property
are compared. The comparison is the ratio of the other
amount to the unit.
In 1996 I wrote about this to Metrologia in a comment on a paper by
J. deBoer "On the History of Quantity Calculus and the International
System" Metrologia 1994/95 32 405-429. I discussed logical errors deBoer
makes in the meaning of words. In some places quantity means a kind; in
other places quantity means how much.
Metrologia did not print my comments, because they are "not scientific".
(I did not mean to say that they were.) I read between the lines that
Metrologia and BIPM are not interested in promoting SI to the general
public.
This awkward use of "quantity" is over 100 years old. As NIST has told me,
metrologists are not going to change.
So, how can we talk to the public with this bad use of words (bad diction)?
I do not say mass and length are quantities. They are properties.
I make only limited reference to the SI brochure and SI 10.
SI is so simple that even grow-ups can use it. Let us keep it simple.
Robert Bushnell PhD PE
member and former treasurer of USMA
chair, ASTM committee E43 on SI
