On Jun 20 , at 3:45 AM, Pat Naughtin wrote:
> The word, system is almost always used incorrectly when it is used in
> expressions such as in 'English system', 'Imperial system' or 'USA system'.
> The word, system, is totally wrong because, before the invention and
> subsequent development of the metric system, there never was any other
> attempt at forming a complete measuring system
Pat,
I think you are thinking too narrowly here. Firstly, no one every refers to the
older units as (for example) "the Old English COMPLETE system" or "the US
Customary COMPLETE System", etc. They are just called "systems", without any
mention of being complete. A group of things can form a system without
necessarily being complete. It is not "totally wrong" to call it a system just
because it is not a complete system.
When I studied physics in college (Rensselaer Polytechnic Institute), we had
four "systems" of units that we learned. They were:
the English "absolute" system
(based in part on the slug as the mass unit and the pound as the
calculated force unit)
the English "gravitational" system
(based in part on the pound as the unit of mass and the poundal as the
calculated force unit)
the cgs metric system
(based on the centimetre of length, the gram of mass, and the second of
time)
and
the MKS metric system
(based on the metre of length, the kilogram of mass and the second of
time).
(I'm not certain of the specific words that were used to name the English
systems and I have put in quotes the terms of which I am not sure.)
Each of these was a "system", although no one ever claimed that any of them
were "complete" in the sense of including measurements for all possible
physical quantities. The MKS system was enlarged from purely mechanical units
to include electrical units when we got to electricity. It was then called the
MKSA system. (There was another system that used a different basic unit for
electrical charge, and also used centimetres for distance and dynes for force.
I don't recall much more about that system.) Te MKSA system was more inclusive
than MKS, but still not presented to be anything like a complete system.
Each of these "systems" worked just fine within the range of measures for which
they were intended. Each may properly be called a system, even though none are
complete like SI is.
Bill Hooper
73 kg body mass*
Fernandina Beach, Florida, USA
* plus or minus a kilogram or so.
