The medical world is by no means consistent with respect to millimeters
and centimeters. Gastroenterologists, for example, specify polyp and
lesion sizes in millimeters. Cardiologists, on the other hand, report
the effective cross-sectional areas of heart valves in square centimeters.
Bill
------------------------------------------------------------------------
Bill Potts
WFP Consulting <http://wfpconsulting.com/>
Roseville, CA
http://metric1.org <http://metric1.org/> [SI Navigator]
------------------------------------------------------------------------
*From:* [email protected] [mailto:[email protected]]
*On Behalf Of *Martin Vlietstra
*Sent:* Sunday, August 02, 2009 11:32
*To:* U.S. Metric Association
*Subject:* [USMA:45480] Re: centimetres vs millimetres
The underlying rationale for SI is to provide a system of
measurement that can be used by all people for all time. While it
is true that certain industries in Europe have adopted different
standards – engineering tends to use millimetres, but medical and
clothing industries use centimetres. If the US is to reap the full
benefit of using metric units, then they should use the same units
as the rest of the world – millimetres in engineering and
centimetres for clothing and in the medical profession.
------------------------------------------------------------------------
*From:* [email protected] [mailto:[email protected]]
*On Behalf Of *Pat Naughtin
*Sent:* 31 July 2009 07:58
*To:* U.S. Metric Association
*Subject:* [USMA:45475] Re: centimetres vs millimetres
On 2009/07/31, at 8:01 AM, [email protected]
<mailto:[email protected]> wrote:
Centimeters is the industry common measurement for cycling
(frames) and skiing....so I use them regularly. But this is
like the meter vs metre argument. Who cares as long as it's not
inch-foot-pounds!!!!
Dear Brian,
To answer your question – I care.
As you know people in the USA have been trying to achieve a
rational, fair, and honest measurement method since decimal methods
were first proposed by Thomas Jefferson in the 1770s, 1780s, and
1790s (as you can see he was persistent). Jefferson succeeded with
decimal currency with help from Benjamin Franklin and George
Washington but he did not succeed in the USA with his proposal for
decimal measurements.
Although Jefferson was not successful with his proposal for decimal
measurements in the USA, it is true that Thomas Jefferson with
support from Benjamin Franklin was successful in promoting the idea
for a /decimal metric system/ in France while he was ambassador
there from 1784 to 1789.
So the truth of the matter is that the USA has been trying to adopt
a better method of measuring – than the one they have now – since
the 1780s.
Now you may not care that the process has taken 225 years so far –
but I do. And I find it incredibly frustrating that you can propose
for the inevitable upgrade to the metric system should take a
further 100 years or more because of your conjecture that there is
an equality between metrication using millimetres or centimetres.
As a challenge, could you describe to us on this list where you have
seen a smooth, fast, economical transition to the metric system that
took less than two years using centimetres. I know of many that have
done this using millimetres.
By the way, most of my bike riding friends use millimetres for
frames and fittings except for old pre-metric specifications of some
threads on old bikes. It is interesting that people who are
developing new ideas for bikes in the USA routinely use millimetres:
See http://www.freepatentsonline.com/5842712.html
and http://www.patentstorm.us/patents/5842712/description.html It
may be that the centimetres you have met are part of a dumbing down
process specifically for sales in the USA because bike sales staff
don't have any industry guidance on which is best to use what to use
– centimetres or millimetres.
With respect to skis, the transition from old pre-metric measures
began in Switzerland and France following the 'International metric
conference' held in about 1798/1799. Given that it is possible to
make a metric transition in two years using millimetres this would
mean that the ski industry was able to do this by 1801. We know that
this didn't work in France until 1840 at least and, without
knowledge, I suspect that a similar time lag was also true of
Switzerland.
Cheers,
Pat Naughtin
Author of the forthcoming book, /Metrication Leaders Guide/.
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has
helped thousands of people and hundreds of companies upgrade to the
modern metric system smoothly, quickly, and so economically that
they now save thousands each year when buying, processing, or
selling for their businesses. Pat provides services and resources
for many different trades, crafts, and professions for commercial,
industrial and government metrication leaders in Asia, Europe, and
in the USA. Pat's clients include the Australian Government, Google,
NASA, NIST, and the metric associations of Canada, the UK, and the
USA. See http://www.metricationmatters.com
<http://www.metricationmatters.com/>for more metrication
information, contact Pat at [email protected]
<mailto:[email protected]> or to get the free
'/Metrication matters/' newsletter go
to: http://www.metricationmatters.com/newsletter to subscribe.
-------- Original Message --------
Subject: [USMA:45469] centimetres vs millimetres
From: Pat Naughtin <[email protected]
<mailto:[email protected]>>
Date: Thu, July 30, 2009 2:50 pm
To: "U.S. Metric Association" <[email protected]
<mailto:[email protected]>>
Dear Tom,
I take exception to the expression, /anti-centimeter prejudice/.
As you know, I am opposed to the use of the centimetre in
almost all* practical daily calculations, but this is not on
the basis of an /anti-centimeter prejudice/.
My opposition to the centimetre is based on observations of
metrication transitions. I simply observed that metrication
using millimetres
can be done quite quickly, smoothly, and with so little cost that
savings are made almost as soon as you begin the metrication process. On the
other hand, the attempts at metrication using centimetres are slow – painfully
slow, rough – often involving bitter disputes about the 'right' way to go about
metric conversion, and so expensive that these metric conversion attempts are
often abandoned with the thought best expressed as: '/Never
again!/'
As you may recall, I did not understand why it was so much
better to choose millimetres rather than centimetres for your
inevitable transition to the metric system, so I involved
myself in any debates and discussions that I could to collect
the arguments both for and against millimetres and centimetres
that I could find. My collection of these thoughts is
available
from http://www.metricationmatters.com/docs/centimetresORmillimetres.pdf
and I know that it is rather long because I tried to be
exhaustive to be fair to both sides of the argument.
* I sometimes – rarely – use centimetres as the basis for
cubic centimetres to get the volume of things like a home
aquarium in millilitres. However, this does not justify, in my
opinion, condemning an entire nation to something like 100
years of metric conversion using centimetres when I have seen
the the whole job done in a day using millimetres. As you know
the USA were world leaders in measurement reform from the
1770s to the 1790s but they have not yet succeeded in fully
adopting the /decimal metric system/ that they had played such
a big part in
producing. See http://metricationmatters.com/USAmetricsystemhistory.html
for a short summary of this history
Cheers,
Pat Naughtin
Author of the forthcoming book, /Metrication Leaders Guide/.
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin,
has helped thousands of people and hundreds of companies
upgrade to the modern metric system smoothly, quickly, and so
economically that they now save thousands each year when
buying, processing, or selling for their businesses. Pat
provides services and resources for many different trades,
crafts, and professions for commercial, industrial and
government metrication leaders in Asia, Europe, and in the
USA. Pat's clients include the Australian Government, Google,
NASA, NIST, and the metric associations of Canada, the UK, and
the USA. See http://www.metricationmatters.com
<http://www.metricationmatters.com/>for more metrication
information, contact Pat
at [email protected]
<mailto:[email protected]> or to get the
free '/Metrication matters/' newsletter go
to: http://www.metricationmatters.com/newsletter to subscribe.
On 2009/07/30, at 9:10 PM, Tom Wade wrote:
It is good of you to promote metric height numbers.
However, I do not like centimeter.
I want schools to stop teaching and using centimeter.
I also want schools to stop teaching inch-pound numbers.
So, I want height to be in millimeters.
What is it with the anti-centimeter prejudice that many people
have on this group ?
Just because mm are more appropriate for nearly all industrial
use doesn't mean the humble cm doesn't have a role. To place
cm alongside inch-pound as in the above paragraph is way over
the top, and to try and pretend that that units between kilo
and milli don't exist is to miss out on a huge advantage of
the use of metric prefixes: the ability to scale the unit to
the most appropriate size (and to advocate not teaching a unit
that is not only officially recognized but is in wide use
internationally simply because purists have a dislike of them
is to recommend leaving holes in young people's education).
The fact is that cm *are* the most appropriate unit for
people's height. If you don't like using cm, then quote your
height in meters (which is effectively 'hidden centimeters'
as you will typically quote it to two decimal places, i.e.
centimeters). Thus the centimeter is the unit that is closest
to the required precision for people's height. It also gives
a nice manageable range of whole numbers.
My height is 174 cm or 1.74 m. If I am writing it down, I may
write '1.74 m', but in saying it, I will say "one seventy
four" without any units, which can be understood as one
hundred seventy four centimeters or 1 meter plus 74 centimeters.
Quoting height in millimeters is simply plain stupid - height
is never expressed with that precision, as something as simple
as a haircut will change your height. People who insist on
using mm for height are like people who are so impressed with
a screwdriver as a tool, that they think it can be used for
everything (whereas a less generally useful tool such as a
hammer would be more appropriate for *some* applications). I
doubt very much you will see mm being used for height in
countries where metric is the system used. Also, using mm for
height gives an unnatural feeling, rather like the putative
"New York 96.56 km" sign that anti-metric activists insist
would replace a more natural "60 mile" sign.
As for the choice of using meters or centimeters, I would
point at that the use of centimeters has the advantage of
yielding a whole integer without the need for decimal places
-- something that is often (quite correctly) pointed out by
people recommending the advantages of mm over inches or
centimeters in other applications such as engineering
drawings. Why not apply the same logic here ?
Use the unit that is best suited to the range and precision
required by the application.
Tom Wade
