Metric Typographic Units and Font Sizes
Markus Kuhn
Metric Typographic Units
------------------------
Typography is an old art and has developed over the years a
bewildering variety of mutually incompatible units. The old Roman
foot/inch system did not offer originally a unit fine enough for
typography, so for instance the following special purpose ad-hoc
units were created in various regions:
1 point (US) = 0.3515 mm = 1/72.27 inch
1 point (Postscript) = 0.3528 mm = 1/72 inch
1 point (Truchet) = 0.188 mm (obsolete today)
1 point (Didôt) = 0.376 mm = 1/72 of a French royal inch (27.07 mm)
1 pica (US) = 4.218 mm = 12 points (US)
1 pica (Postscript) = 4.234 mm = 12 points (Postscript)
1 cicero = 4.531 mm = 12 points (Didôt)
Resolutions of output devices are frequently specified in dpi (dots
per inch), which is the reciprocal value of the pixel size multiplied
with 25.4 mm.
With the metric system, we have now a well established,
consistent, and universally accepted set of length units, ranging
from subatomic to cosmological dimensions. The use of archaic
ad-hoc special purpose units has become obsolete and should be
strongly discouraged.
It would be very convenient if the typographic community would
abandon this unit mess and switch to the metric system. Metric
typographic units are already used in Japan and to some degree in
Germany and other European countries. However, the market
dominance of US-originated typographic software without proper
support for metric units at all levels currently hinders the further
deployment of metric typographic practice.
Metric typography as described in the new German draft standard
DIN 16507-2 works roughly as follows: Absolutely everything is
measured and specified in millimeters. Dimensions are multiples of
0.25 mm, or where a finer resolution is required multiples of 0.1 or
0.05 mm. No more points, picas, ciceros, inches, etc. and all their
awful conversion factors. There is nothing wrong with continued
use of font specific units such as the em, as these are not absolute
length measurements.
Japanese typesetters use the unit Q (quarter) for font sizes, where
1 Q = 0.25 mm, i.e. the same modulus recommended by DIN
16507-2.
Metric Font Sizes
-----------------
DIN 16507-2 defines (among many others) the following two font
measures:
Font Size (German: Schriftgröße)
This is the baseline distance for which the font was
designed. A font should normally be identified and selected
by this size, because the intended baseline distance is
much more relevant for practical layout work than the
actual dimensions of certain characters.
Font Height (German: Oberhöhe)
This is the height in mm of letters such as k or H. Typically,
the font height is around 72% of the font size, but this is of
course at the discretion of the font designer.
If we write say "Helvetica 5.0", then this means we have a font that
was designed for a 5 mm line spacing. It will typically have an H
that is 3.6 mm or 10.2 points tall (72% of 5 mm). Calculations
become trivial: in a 60 mm high column, we can write exactly 60 mm
/ 5 mm = 12 lines. The baselines of text become neatly aligned with
a millimeter grid, and if millimeters are used to describe both font
size and font height, their relationship becomes easier to handle
than if different units such as mm and points were used. Layout
designers do not have to juggle any more with conversion factors
such as 72.27 and 25.4. If you write "Helvetica 5.00/5.25" then this
means that you use exactly the same font as above, but with 0.25
mm more baseline skip than it was designed for.
DIN 16507-2 contains a list of preferred metric font sizes, together
with the corresponding preferred 72% font heights in mm. The table
below shows in addition to these values from the standard also the
corresponding preferred 72% font heights in Postscript points for
easier comparison with the old font sizes. Note: the point sizes of
US fonts do not always refer to the k/H height that is defined by
DIN as the font height. Some font manufacturers (e.g., Knuth) also
refer to the size of taller characters such as "(", so be careful not to
convert incompatible measurements and try to find out the baseline
distance for which a font was originally designed of you want to
convert properly to metric sizes.
Font Size Font Height | Font Size Font Height
[mm] [mm] [pt] | [mm] [mm] [pt]
-----------------------------+----------------------------
1.5 1.1 3.1 | 6.0 4.3 12.2
1.75 1.3 3.6 | 7.0 5.0 14.3
2.0 1.4 4.1 | 8.0 5.8 16.3
2.25 1.6 4.6 | 9.0 6.5 18.4
2.5 1.8 5.1 | 10.0 7.2 20.4
2.75 2.0 5.6 | 12.0 8.6 24.5
3.0 2.2 6.1 | 14.0 10.1 28.6
3.25 2.3 6.6 | 16.0 11.5 32.7
3.5 2.5 7.1 | 18.0 13.0 36.7
3.75 2.7 7.7 | 20.0 14.4 40.8
4.0 2.9 8.2 | 22.5 16.2 45.9
4.25 3.1 8.7 | 25.0 18.0 51.0
4.5 3.2 9.2 | 27.5 19.8 56.1
5.0 3.6 10.2 | 30.0 21.6 61.2
5.5 4.0 11.2 | 35.0 25.2 71.4
(The above mm values are from an old DIN 16507-2 draft. If you
implement metric font sizes, please make sure you get the latest
version of the actual standard from DIN <http://www.din.de/>.)
Again: The font size refers to the baseline distance for which the
font was designed, and is used to generally identify the font. The
font height is the actual height of characters such as H or k. The
font height is typically 72% of the font size as a preferred value, but
this is of course left to the discretion of the font designer. One
writes "Courier 6.0" to get the Courier font designed for 6 mm
baseline distance (where the height of an H is typically 4.3 mm or
12.2 pt), and one writes "Courier 6.0/9.0" to get the same font but to
use it with 50% more space between the lines.
Metric Device Resolutions
-------------------------
Instead of giving a reciprocal pixel size in dpi, it would be much
more convenient to specify the pixel size directly in micrometers,
as it is also common practice in the semiconductor industry. For
instance a 2540 dpi phototypesetter has a pixel size of 10 µm, and a
600 dpi laser printer has a pixel size of 42.33 µm.
Metric Modes in Layout Software
-------------------------------
While US-originated typographic software frequently does allow to
switch into some sort of metric mode, these metric modes usually
have lots of loose ends and were obviously never used in daily work
by their developers. Add-on metric modes often suffer from bizarre
rounding bugs (you enter 210 mm and always get ugly 209.902777
mm displayed, alignments on metric grids do not work out, startup
defaults are often fixed to US units, etc.), and the metric support
stops at critical details like the font or pixel size, such that in the
end metric users still have to constantly convert between
millimeters, points, inches, and 1/inches. US developers should
realize that over 95% of the world population grew up using the
metric system and that it is therefore prudent to design a system
today from the very lowest level up purely in metric units.
Conversion to archaic units like the inch and the various points
should only be an add-on feature in the user interface on top of an
underlying purely metric architecture, and not the other way round.
Literature
----------
The titles of some relevant DIN standards are
DIN 16507-1, Ausgabe: 1998-09, Drucktechnik -
Schriftgrößen, Maße und Begriffe - Teil 1: Bleisatz und
verwandte Techniken
(Norm-Entwurf) DIN 16507-2, Ausgabe: 1998-04,
Drucktechnik - Schriftgrößen - Teil 2: Digitaler Satz und
verwandte Techniken
Unfortunately, these seem to be available at the moment only in
German. I hope that a standardization group such as ISO/TC130
will eventually set up a very similar international guideline for the
use of metric font sizes.
Further recommended literature about using the metric system in
typography:
Otl Aicher: Typographie. 2. Aufl, 1989. (bilingual:
German/English)
Markus
--
Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
J.Ma...@let.kun.nl
Age which we are still hugging today as if they were part of the greatest
achievements of mankind. So also goodbye to lpi and dpi! In Europe we used
the Didot system; the coming of the computer did nothing at all to bring real
progress here, as it brought us the inch based typographic systems. Now, at
last metrication in this area is in reach. It also shows that the metric
system, in contradiction to the claims of F2M and the BWMA can use binary
divisions all right where suitable. The A-paper sizes are another example.
Each A-size has its number so that the binary fractions themselves can be
ignored.
J. Maenen
In article <77tc1i$gji$1...@pegasus.csx.cam.ac.uk>,
mg...@cl.cam.ac.uk (Markus Kuhn) wrote:
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
Ian Kemmish
>
>With the metric system, we have now a well established,
>consistent, and universally accepted set of length units, ranging
``Universally accepted''? Do the Merkuns know about this? :-)
>from subatomic to cosmological dimensions. The use of archaic
>ad-hoc special purpose units has become obsolete and should be
>strongly discouraged.
The use of old units should be encouraged as it maintains the ability for
mental arithmetic, which can only be good news. Only a few weeks ago I had to
help a bewildered shopper in the supermarket because she could no longer buy
the ingredients for her mother's Christmas cake recipe in the correct
amounts....
>by their developers. Add-on metric modes often suffer from bizarre
>rounding bugs (you enter 210 mm and always get ugly 209.902777
>mm displayed, alignments on metric grids do not work out, startup
>defaults are often fixed to US units, etc.), and the metric support
Surely the strongest possible argunent for switching to nice round, convenient
inches for typographical and layout work? :-)
Not to mention the fact that letter being shorter and fatter than A4 makes
viewing letter-format PDF files on screen a lot more convenient than viewing
A4-format PDf files on screen. And I find letter a lot more pleasing
aesthetically too.
> US developers should
>realize that over 95% of the world population grew up using the
>metric system and that it is therefore prudent to design a system
No -- many of that 95% were brought up on Imperial and other measures. Many
countries have only converted in the past few decades and contain a large
numberof consumers, forced to switch, who have trouble dealing with metric
weather forecasts and packaging.
Just playing light-hearted Devil's Advocate, but this kind of whinge doesn't
belong in comp.lang.postscript in the first place....
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Ian Kemmish 18 Durham Close, Biggleswade, Beds SG18 8HZ, UK
i...@five-d.com Tel: +44 1767 601 361
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Behind every successful organisation stands one person who knows the secret
of how to keep the managers away from anything truly important.
Peter Flynn
>
> <http://www.cl.cam.ac.uk/~mgk25/metric-typo.html>:
>
> Metric Typographic Units
> With the metric system, we have now a well established,
> consistent, and universally accepted set of length units, ranging
> from subatomic to cosmological dimensions. The use of archaic
> ad-hoc special purpose units has become obsolete and should be
> strongly discouraged.
When the decimal system will let me provide an exact value for
fractions like a third or a sixth then I might consider it :-)
> Germany and other European countries. However, the market
> dominance of US-originated typographic software without proper
> support for metric units at all levels currently hinders the further
> deployment of metric typographic practice.
I agree. But I uses a system which can handle any dimension in any
unit in common use, and for computation uses an internal measurement
smaller than the wavelength of visible light. I find this gives me
adequate control.
[lots of useful information snipped]
This futile exercise in trying to force the real world into a
suit of clothes constructed by a committee is fine for interchange,
when you want to be certain you are talking the same measurements,
but what happens if I just don't want to use a millimeter grid?
I use millimeters a lot of the time...I just finished a job for
which the SGML source specified image placement and font alignment
in mm. It's never caused me any trouble and I doubt it ever will:
I think in mm just as easily as in inches or picas, but when I am
deciding on dimensions for my own purposes, I reserve the right to
pick whichever ones I wish, and not be told by a committee.
///Peter
--
DTDs are not common knowledge because programming students are not
taught markup. A markup language is not a programming language.
Andreas Berghauer
>
> <http://www.cl.cam.ac.uk/~mgk25/metric-typo.html>:
>
> Metric Typographic Units
> ------------------------
>
> Schriftgrößen, Maße und Begriffe - Teil 1: Bleisatz und
> verwandte Techniken
>
> (Norm-Entwurf) DIN 16507-2, Ausgabe: 1998-04,
> Drucktechnik - Schriftgrößen - Teil 2: Digitaler Satz und
> verwandte Techniken
>
Markus, SGML-friends,
for sure, we do need standardisation.
- SGML : where would we be without rhe "S" - lost in hyperspace like the
HT- and as it seems to be uptil now the X-community.
- English : I can write this from my Cologne secretary and know, that,
say, 90% of the readers will be able to read it (it may require some
fuzzy-logic to do so).
- Screws: Aren't we lucky, that we can buy a M3x10 screw, with some
extra numbers following the DIN (ISO?) declaration will be identical
around the world ("universally")?
- Last night I explained to my 7 year old son, that because of the
decimal system he is able to calculate with "large numbers" using small
number's arithmatic.
This being the bright side of standardisation.
In Europe there's an institution called European Commitee, which claims
the right to standardize anything from screws to underwear sizes (see
above: bright side). That's when a DIN standardisation becomes a EN.
EC example for the dark side: Apples with a diameter below a certain are
not to be sold but dumped.
Another very dark standardistion on the way: When is a person worth to
be kept alife? Meaning, when should a person in a hospital being in a
critical state be "unplugged". Your death certificate would read: Cause
of death: unworthy according to EN NS666. Framemaker's Thesaurus reads
for "unworthy": "valueless", "no-good", "useless", "inferior". I hope
they haven't forgotten, what had happened in Germany some 55 years ago.
Back to real life. Let's see "the bright side". And I've got so used to
12 pt Times, that I can live with both - just like Peter Flynn said in
his posting (Peter: a third or squareroot 7 are general
analog-to-digital problems; that's why airplane's steering systems had
been using analogue computers for a long time). But it would be great if
software would _really_ use the system _I_ want, doing conversions as
little as possible (Markus' example wasn't to bad, like .05% off).
So far my personal thoughts on this thread.
Farewell ye friends,
Andreas Berghauer.
am...@nsof.co.il-n0spam
>The use of old units should be encouraged as it maintains the ability for
>mental arithmetic, which can only be good news. Only a few weeks ago I had to
>help a bewildered shopper in the supermarket because she could no longer buy
>the ingredients for her mother's Christmas cake recipe in the correct
>amounts....
Mental arithmetic? Try this: how many 30-ft railway bars are needed to
span 3 miles? There's a conspiracy of industrialists and government
officials in the US to keep the metric system out of reach of the public,
by selling flour in 226.8 (0.5lb) gram packages, or posting signs in
national parks that say "ELEVATION 609.6m (2000ft)".
This leaves the general public with the impression that the metric system
is very accurate but complicated, to be used only by scientists. They
are horrified of the prospect of having to do mental arithmetic of "how
many 9.144m bars are needed to span 4.828 Km", not realizing that if
everyone went metric, such a problem would be reduced to "how many 10m
bars are needed to span 5 Km".
--
Amos Shapir
Paper: nSOF Parallel Software, Ltd.
Givat-Hashlosha 48800, Israel
Tel: +972 3 9388551 Fax: +972 3 9388552 GEO: 34 55 15 E / 32 05 52 N
Markus Kuhn
|> Not to mention the fact that letter being shorter and fatter than A4 makes
|> viewing letter-format PDF files on screen a lot more convenient than viewing
|> A4-format PDf files on screen.
Mentally flexible people just turn their Monitor 90° to have the
right aspect ratio. Screen drivers to support this are available
for all major platforms. I never understood, why people consider
the 4:3 screen format to be particularly preferably for computer
usage, but then, people tend not do consider anything at all and
just prefer to follow the herd. Writing PDF files in a 4:3 aspect
ratio if they are intended for on-screen display is another
option. Using a markup language (e.g., HTML, XML) instead of a
page formatting language (e.g., PDF) and letting the output device
do the actual formatting at the discretion of the receiving user is
clearly the best approach. But just claiming that the US Legal paper
thanks to being 6% shorter is much better than A4 because of PDF
screen displaying on 4:3 monitors does not at all demonstrate
impressive insight in matters of online publishing.
Michael J Downes
> With the metric system, we have now a well established,
> consistent, and universally accepted set of length units, ranging
> from subatomic to cosmological dimensions. The use of archaic
> ad-hoc special purpose units has become obsolete and should be
> strongly discouraged.
Whether it should be discouraged in general is open to debate. I do
not disagree that worldwide standards of measurement for particular
kinds of manufactured goods are beneficial for international trade.
But does it follow that forcing *all* measurements of distance into
the framework of the metric system is therefore good? Non sequitur.
On the contrary, it is clear that different domains of measurement
have different natural units. For example, astronomical distances are
measured in light-years, not terameters. And the natural numbers to
use for shoe sizes would have something to do with the average
variation in the length of the foot that can be accommodated before a
pair of shoes becomes uncomfortably small or large. If that distance
is not a power-of-10 fraction of a meter then forcing shoe
manufacturers to use metric units for shoe sizes is like forcing
someone to wear ill-fitting shoes. It can be done, yes, but why?
I would guess that the natural unit to use for rule thickness in
typography is the smallest change in thickness that is readily
perceptible to the human eye. The natural unit for type sizes is the
smallest change in type size that can be readily distinguished by the
human eye---and this is probably different from the natural unit for
rule thickness, and from the natural unit for measuring interword
spaces ...
> Japanese typesetters use the unit Q (quarter) for font sizes, where
> 1 Q = 0.25 mm, i.e. the same modulus recommended by DIN
> 16507-2.
Which clearly suggests that either the mm unit or the base 10 is
ill-suited for this particular application.
> It would be very convenient if the typographic community would
> abandon this unit mess and switch to the metric system. Metric
> typographic units are already used in Japan and to some degree in
> Germany and other European countries. However, the market
> dominance of US-originated typographic software without proper
> support for metric units at all levels currently hinders the further
> deployment of metric typographic practice.
I'm not too keen on the idea until the metric system itself is
corrected so that the meter is a power-of-10 multiple of some natural
unit related to the speed of light, which is now known to be a better
way of defining distance than the archaic, ad hoc subdivision of the
earth's circumference used 200 years ago by the French scientists who
first defined the length of a meter.
The meter is now defined, retroactively, as the distance light travels
through a vacuum in 1/299,792,458 of a second. That's inconsistent
with the fundamental premises of the metric system in two ways: it's
not a power of 10, and it's defined in relation to time units which
are themselves base 12/base 60. (As a matter of fact if you change the
ratio to the nearest power of 10: 1/1,000,000,000, then the natural
human-scale unit of distance according to the original principles of
the metric system turns out to be 11.8028 inches, or pretty darn close
to *one foot*.)
A counter-argument will doubtless be that the metric system is by
now too widely accepted to permit change in the defined length of a
meter. "Change would be too costly." But this argument is equally
valid as a reason *not* to switch to the metric system for anyone that
has not switched yet. Such as typographers.
There is also some sentiment that the use of a decimal system of
numbers is archaic and ill-founded (since 10 is divisible only by 2
and 5), and that the base-12/base-60 system used for our time units
and units of angular measurement is mathematically speaking a better
choice. So, to have 12 points per pica and 12 inches per foot may not
be such a bad idea after all.
Paul L. Allen
Michael J Downes <eps...@ams.org> writes:
> mg...@cl.cam.ac.uk (Markus Kuhn) writes:
> > Japanese typesetters use the unit Q (quarter) for font sizes, where
> > 1 Q = 0.25 mm, i.e. the same modulus recommended by DIN
> > 16507-2.
>
> Which clearly suggests that either the mm unit or the base 10 is
> ill-suited for this particular application.
In fact it goes against *all* metric precepts to have a unit of 0.25
mm. Metric (rightly or wrongly) did away with subunits that were halves,
quarters or other fractions of a base unit, with the exception of the
fraction 1/10. The only way you can fit 0.25mm into the metric
philosophy is if 0.20, 0.21, 0.22,... 0.29 are also permitted.
--Paul
Louis Vosloo
company. At this point only the most exclusive powers resist use of this
revolutionary idea: Brunei, North Yemen and the US (*). And in one of those
places time is based on local solar time. What a great idea: no time zones,
no discrete jumps in time as you move east to west! Yes, lets try that.
Besides, the US switched to the metric system years ago. Congress has passed
several laws in this regard over the past two centuries (way before the Brits).
Jefferson brought such revolutionary ideas back from Paris (where he apparently
was distracted by more than revolutionary ideas).
Just somehow nobody paid any attention to the laws being passed (except for
a few odd things like wine bottles, which have to be 750 ml now).
By the way, I have seen some of the most vociferous arguments on news groups
from people who insist on using Angstroms and hectars and other such
deprecated units. Or people who clearly never got passed using cgs,
which predates mks, which predates SI. And ghee, wasn't SI adopted
nearly half a centruy ago?
(*) I am curious to know whether there are any others. Somehow I remember
hearing there might be 5 countries in this club, but I can't remember the others...
Rebecca and Rowland
> I am looking forward to see this standard replace the systems from the Stone
> Age which we are still hugging today as if they were part of the greatest
> achievements of mankind. So also goodbye to lpi and dpi! In Europe we used
> the Didot system;
<ahem> Not in my part of Europe.
Rowland.
[snip]
--
Remove the animal for my email address: reb...@astrid.dog.u-net.com
Sorry - the spam got to me. PGP pub key A680B89D
UK biker? Join MAG and help keep bureaucracy at bay
http://dredd.meng.ucl.ac.uk/www/mag/mag.html
Rebecca and Rowland
[snip]
> In Europe there's an institution called European Commitee, which claims
> the right to standardize anything from screws to underwear sizes (see
> above: bright side). That's when a DIN standardisation becomes a EN.
>
> EC example for the dark side: Apples with a diameter below a certain are
> not to be sold but dumped.
Other down sides: bent cucumbers can't be sold either, nor seeds that
aren't on the official list. Yes, the EU has laws designed to reduce
biodiversity.
[snip]
> Back to real life. Let's see "the bright side". And I've got so used to
> 12 pt Times, that I can live with both - just like Peter Flynn said in
> his posting (Peter: a third or squareroot 7 are general
> analog-to-digital problems; that's why airplane's steering systems had
> been using analogue computers for a long time).
Not only that, but also because an analogue computer can't crash in the
same way a digital computer can. It's also much harder for an analogue
computer to produce complete rubbish as output due to a mistake in
`programming' (i.e., design). Me, I'd prefer to trust the old-fashioned
fly-by-wire, where the pilot's muscles move the control surfaces (via
steel wires running through the 'plane), maybe with a bit of help from
servo motors if neeed.
[snip]
Rowland.
Joseph Hertzlinger
most efficient possible system for doing mental arithmetic, we should
get rid of both the metric system and the Anglo-American system as well
as decimal arithmetic in favor of a dozenal system. After all, across
the universe, there are surely more species are using a dozenal system
than a decimal system.
Andreas Berghauer
>
> Markus Kuhn schrieb:
<..>
> >
<(Markus' example wasn't to bad, like .05% off).
>
> So far my personal thoughts on this thread.
>
> Farewell ye friends,
>
> Andreas Berghauer.
Paper A4-size should have sidelengths of 0.2102241038134m and
02973017787507m to get to the suppossed 0.0625 (1/16) sqmeters.
But it's usually sold 0.21x0.297 which results in 0.6237 sqmeters, which
is -0.208% off (that's the where the paper producers make their living
of).
Or it is seen as 0.21x0.3 which would be 8% off.
:-)))
Andreas Berghauer
Jan Roland Eriksson
>The best argument for the US not switching to SI is that it is in such distinguised
>company. At this point only the most exclusive powers resist use of this
>revolutionary idea: Brunei, North Yemen and the US (*). And in one of those
>places time is based on local solar time. What a great idea: no time zones,
>no discrete jumps in time as you move east to west! Yes, lets try that.
Being a natural born European with several years of experience from work
in American Industries I think I can say that a lot of them have changed
to metrics in the last decade.
New machine installations in steel mills are usually designed with
metric dimensions. The car industry has really seen the advantage of
using metric as their base since that simplifies the use of components
on different continents. Components used in Asian and European Fords are
the same as in American Fords etc...
>Besides, the US switched to the metric system years ago. Congress has passed
>several laws in this regard over the past two centuries (way before the Brits).
>Jefferson brought such revolutionary ideas back from Paris (where he apparently
>was distracted by more than revolutionary ideas).
>Just somehow nobody paid any attention to the laws being passed (except for
>a few odd things like wine bottles, which have to be 750 ml now).
Most American mechanical and electrical engineers that I have worked
together with are fully fluent in both systems in fact.
>By the way, I have seen some of the most vociferous arguments on news groups
>from people who insist on using Angstroms and hectars and other such
>deprecated units.
Deprecated or not, these are all metric based units.
1 are = 10x10 meters
1 hectare = 100 ar = 100x100 meters
1 Angstrom = 10^-10 meters
Ar, Hectare, Angstrom, kilograms, millimeters, centimeters, kilometers,
etc, are just names (with some meaning of course) for various types of
factor 10^x units of the meter.
--
Jan Roland Eriksson <r...@css.nu> <URI:http://css.nu/>
Bodo Moeller
> <http://www.cl.cam.ac.uk/~mgk25/metric-typo.html>:
> Metric Typographic Units
> ------------------------
> Typography is an old art and has developed over the years a
> bewildering variety of mutually incompatible units. The old Roman
> foot/inch system did not offer originally a unit fine enough for
> typography, so for instance the following special purpose ad-hoc
> units were created in various regions:
> 1 point (US) = 0.3515 mm = 1/72.27 inch
> 1 point (Postscript) = 0.3528 mm = 1/72 inch
> 1 point (Truchet) = 0.188 mm (obsolete today)
> 1 point (Didôt) = 0.376 mm = 1/72 of a French royal inch (27.07 mm)
> 1 pica (US) = 4.218 mm = 12 points (US)
> 1 pica (Postscript) = 4.234 mm = 12 points (Postscript)
> 1 cicero = 4.531 mm = 12 points (Didôt)
There's also the metric point (whatever its official name is), which
is defined to be exactly 0.375 mm (thus providing a unit which is very
close to the relevant other definitions of "point" while allowing
exact computations in the metric system).
[...]
> Metric Font Sizes
> -----------------
> DIN 16507-2 defines (among many others) the following two font
> measures:
> Font Size (German: Schriftgröße)
> This is the baseline distance for which the font was
> designed. A font should normally be identified and selected
> by this size, because the intended baseline distance is
> much more relevant for practical layout work than the
> actual dimensions of certain characters.
> Font Height (German: Oberhöhe)
> This is the height in mm of letters such as k or H. Typically,
> the font height is around 72% of the font size, but this is of
> course at the discretion of the font designer.
If the majuscule height is approximately 72 % of the "Font Size", then
presumably the "font size" is -- in accordance with the traditional
terminology -- the body size ("Kegelhöhe"); e.g. about 4.23 mm for
what is now called a "12 pt font", if we use Didot points. Actually,
the percentage of the body size that is used for a typical capital
letter ("Font Height") varies between European and US fonts: If I
remember correctly, it's around 67 % or something like that for fonts
based on Didot points, while your 72 % figure looks more like the
U.S. version -- I think foundries chose these values so they could use
the same type designs without scaling for the same point size at
both European and US markets even though the total size of the metal
type was larger in Europe (around 4.51 mm, i.e. 12 Didot points) than
in the US (around 4.23 mm).
This "font size" is _not_ the recommended baseline distance. For most
fonts, the baseline distance should be larger to ensure optimal
readability; only if you want to save space, it may be acceptable to
typeset without leading ("kompreß setzen"). What the font size
certainly is in the case of fonts that were created in metal-type
times is the _minimum_ baseline distance from the font designer's
point of view (but still he might hate you for actually typesetting
that tight :-).
> If we write say "Helvetica 5.0", then this means we have a font that
> was designed for a 5 mm line spacing. It will typically have an H
> that is 3.6 mm or 10.2 points tall (72% of 5 mm). Calculations
> become trivial: in a 60 mm high column, we can write exactly 60 mm
> / 5 mm = 12 lines.
Only if you don't put leading (or its electronic equivalent in the
typical case where no actual metal types are involved) between the
lines. Usually, there will be leading; and then dividing the column
height by the baseline distance in order to compute the exact number
of lines does not work (fencepost error: there's no leading before the
first or after the last line).
Note that typical word processors (as opposed to typesetting software)
may hide the exact leading measures from the user, instead using silly
terms such as "single-spaced typing", "double-spaced typing" etc.
In such cases one might have to measure oneself how much leading is
added (or use saner software, or find the hidden menu which tells the
user things like this).
Rodger Whitlock
>mg...@cl.cam.ac.uk (Markus Kuhn) writes:
>
>> With the metric system, we have now a well established,
>> consistent, and universally accepted set of length units, ranging
>> from subatomic to cosmological dimensions. The use of archaic
>> ad-hoc special purpose units has become obsolete and should be
>> strongly discouraged.
>
>not disagree that worldwide standards of measurement for particular
>kinds of manufactured goods are beneficial for international trade.
>But does it follow that forcing *all* measurements of distance into
>the framework of the metric system is therefore good? Non sequitur.
>
>On the contrary, it is clear that different domains of measurement
>have different natural units.
>Which clearly suggests that either the mm unit or the base 10 is
>ill-suited for this particular application.
I wonder if one of the subtle problems with SI is that a power of ten is
too big a jump between successive units of measurement. Perhaps a system
based on powers of two or four would be better.
>I'm not too keen on the idea until the metric system itself is
>corrected so that the meter is a power-of-10 multiple of some natural
>unit related to the speed of light, which is now known to be a better
>way of defining distance than the archaic, ad hoc subdivision of the
>earth's circumference used 200 years ago by the French scientists who
>first defined the length of a meter.
>
>The meter is now defined, retroactively, as the distance light travels
>through a vacuum in 1/299,792,458 of a second.
Are you sure? The last time I looked the meter was defined in terms of
the wavelength of a specific atomic emission spectrum line, one quite
easy to reproduce. It used to be a line in the cadmium spectrum, but I
think the standard was changed to something even better a good many
years ago.
--
Rodger Whitlock
Carsten Geckeler
> Andreas Berghauer schrieb:
> >
> > Markus Kuhn schrieb:
> <..>
> > >
> <(Markus' example wasn't to bad, like .05% off).
> >
> > So far my personal thoughts on this thread.
> >
> > Farewell ye friends,
> >
> > Andreas Berghauer.
> By the way:
> Paper A4-size should have sidelengths of 0.2102241038134m and
> 02973017787507m to get to the suppossed 0.0625 (1/16) sqmeters.
>
> But it's usually sold 0.21x0.297 which results in 0.6237 sqmeters, which
> is -0.208% off (that's the where the paper producers make their living
> of).
0.21x0.297 is the size according to the ISO/DIN standard. Although the
definition is right that A4 should have an area of 0.0625m^2 and a ration
of sqrt(2), the standard says to round the side length to the nearest
millimeter.
So 0.21x0.297 is absolutely correct.
Cheers, Carsten
Howard W. LUDWIG
> Michael J Downes <eps...@ams.org> wrote [snippage not noted]
> >mg...@cl.cam.ac.uk (Markus Kuhn) writes:
> >
> >> With the metric system, we have now a well established,
> >> consistent, and universally accepted set of length units, ranging
> >> from subatomic to cosmological dimensions. The use of archaic
> >> ad-hoc special purpose units has become obsolete and should be
> >> strongly discouraged.
> >
> >Whether it should be discouraged in general is open to debate. I do
> >not disagree that worldwide standards of measurement for particular
> >kinds of manufactured goods are beneficial for international trade.
> >But does it follow that forcing *all* measurements of distance into
> >the framework of the metric system is therefore good? Non sequitur.
> >
> >On the contrary, it is clear that different domains of measurement
> >have different natural units.
>
> >Which clearly suggests that either the mm unit or the base 10 is
> >ill-suited for this particular application.
>
> I wonder if one of the subtle problems with SI is that a power of ten is
> too big a jump between successive units of measurement. Perhaps a system
> based on powers of two or four would be better.
Some people complain about the number (20) of prefixes to remembernow in SI,
and most of them are separated by factors of 1000, not
10.
In the US customary and imperial systems, the ratios of consecutive
named units for various quantities are not that far from 10, and in
some cases are rather larger:
1 mile = 1760 yards (unless you want smaller numbers using
relatively scarcely used unit names like:
1 mile = 8 furlongs
1 furlong = 40 rods
1 rod = 5.5 yards)
1 yard = 3 feet
1 foot = 12 inches
1 inch = 1000 mils
1 ton = 20 hundredweights
1 hundredweight = 100 pounds (US), 8 stones (imp.)
1 stone = 14 pounds
1 pound = 16 ounces
Volumes used to involve factors of 2 rather consistently, but
practicality led people to drop many of the terms, such as
pottle. Too many names to keep up with is not practical.
>
>
> >I'm not too keen on the idea until the metric system itself is
> >corrected so that the meter is a power-of-10 multiple of some natural
> >unit related to the speed of light, which is now known to be a better
> >way of defining distance than the archaic, ad hoc subdivision of the
> >earth's circumference used 200 years ago by the French scientists who
> >first defined the length of a meter.
In other words, you are saying that metrologists have now reachedthe
ultimate technique in precise measurement of length; no
further improvements will ever be made. That seems like a
risky assumption, given how technology has progressed and is still
doing so.
Yes, the first definition was based on an easy fraction of a
meridianal quadrant of Earth. That was quickly seen to not be a
very convenient, readily repeatably realizable definition, so the
definition changed to be based on etchings on a bar, as close in
separation as possible, given the technology of the day, to the
Earth-based definition. Etchings may look rather fine to the
unaided eye, but are in fact very coarse when trying to measure
high-precision lengths, so a better technique was found using
interferometry, and the definition of the meter was changed to a
certain inconvenient multiple of wavelengths of a particular
emission of krypton; the reason for the inconvenient multiple was
to keep the meter as close as possible to being an unchanging
length. Had the meter been substantially altered to have the
number of wavelengths be a "nice" value, this would have caused a
great deal of upheaval in society's ability to measure and for no
reason. This would have had to be repeated less than a quarter
century later when the krypton-wavelength definition prove to be
inadequately precise, and the speed of light was adopted for the
definition of the meter. Who is to say that it won't change
again? The reason for the strong term "upheaval" is that not only
would rulers be impacted, but the SI (metric) system of units is
just that, a system, so that impacting one quantity substantially
has major impact on other units. Changing the meter would cause
all force, pressure, energy, electrical, and magnetic measurements
to change. The coherent-system aspect of SI is much more
fundamental and important than the power of 10 concept so
frequently touted.
> >
> >The meter is now defined, retroactively, as the distance light travels
> >through a vacuum in 1/299,792,458 of a second.
Granted, this value is not particularly convenient to rememberand use for
precise calculations. However, for most back-of-the-
envelope purposes, 3x10^8 m/s suffices for the speed of light.
In any case, given the availability of calculators and computers,
these odd-ball numbers don't really cause any problem.
> Are you sure? The last time I looked the meter was defined in terms of
> the wavelength of a specific atomic emission spectrum line, one quite
> easy to reproduce. It used to be a line in the cadmium spectrum, but I
> think the standard was changed to something even better a good many
> years ago.
>
Yes, it was changed a good many years ago (1983) to somethingbetter--the
distance light travels in (1 / 299 792 458) s, just
as described above. The previous definition involved krypton,
not cadmium.
> --
> Rodger Whitlock
Howard W. LUDWIG, Ph.D.
Howard W. LUDWIG
In any case, the definition (by various laws, regulations,
treaties, etc.) of the metric system is now regarded as SI.
SI does _not_ in any way regard powers of 10 as important except
for a standard set of prefixes (_no_ special stand-alone names
like "are", "angstrom", "liter", etc. for anything violating
coherency). Coherency, based on a carefully defined, practical
set of base units, is the number one fundamental aspect in the
underlying philosophy of SI (contrary to the case of the original
definition of the metric system in the 1790s). The availability
of a standard set of power-of-10 prefixes (the same set applying
to every unit with a name in the coherent system) provided as a
convenience for handling very large or very small quantities ranks
as a rather distant number two. (To emphasize the distance
of
number two priority, the kilometer and millimeter are not regarded
as units of length in SI--they are named multiples of the one and
only unit of length, the meter.)
As an example, area is the product of two lengths. _The_ unit
of
length in SI is the meter. Therefore, the product of two
lengths
must have units of meter squared--a coherent system requires that
(the meter squared) to be _the_ unit of area, not 100 of them.
Therefore, the "are" has been removed from the metric system, as
defined in SI, now the official definition.
For further guidance, I recommend visiting http://www.bipm.fr/
(the site of the organization responsible, by treaty, for
maintaining the metric system) or http://physics.nist.gov/cuu/index.html
.
--
Jan Roland Eriksson <r...@css.nu> <URI:http://css.nu/>
Howard W. LUDWIG, Ph.D.
Louis Vosloo
> >from people who insist on using Angstroms and hectars and other such
> >deprecated units.
> Deprecated or not, these are all metric based units.
>
> 1 are = 10x10 meters
> 1 hectare = 100 ar = 100x100 meters
> 1 Angstrom = 10^-10 meters
>
> Ar, Hectare, Angstrom, kilograms, millimeters, centimeters, kilometers,
> etc, are just names (with some meaning of course) for various types of
> factor 10^x units of the meter.
This is exactly what I was referring to. 50 years ago with mks it was indeed
just a matter of 10^x. Now with SI only 1000^x should be used (mm, m, km).
Which leaves Angstom (10^-10 m) out in the cold, for example. Along
with several other units named after famous people...
Louis Vosloo
> :As an example, area is the product of two lengths. _The_ unit of
> :length in SI is the meter. Therefore, the product of two lengths
> :must have units of meter squared--a coherent system requires that
> :(the meter squared) to be _the_ unit of area, not 100 of them.
> :Therefore, the "are" has been removed from the metric system, as
> :defined in SI, now the official definition.
>
> absolutely!. Let us know when they do away with the liter.
But isn't the liter OK, because it is a thousand ml :-)?
And a ml is a cubic centimeter. Oops!
Rebecca and Rowland
> mg...@cl.cam.ac.uk (Markus Kuhn) writes:
>
> > With the metric system, we have now a well established,
> > consistent, and universally accepted set of length units, ranging
> > from subatomic to cosmological dimensions. The use of archaic
> > ad-hoc special purpose units has become obsolete and should be
> > strongly discouraged.
>
> Whether it should be discouraged in general is open to debate. I do
> not disagree that worldwide standards of measurement for particular
> kinds of manufactured goods are beneficial for international trade.
> But does it follow that forcing *all* measurements of distance into
> the framework of the metric system is therefore good? Non sequitur.
Who cares about the benefits to trade? The metric system is a Good
Thing because it's a consistent international standard, and it was
adopted for science without a thought for international trade. It's
been adopted for engineering for convenience's sake - having a single
set of thread standards (for example), must have caused a huge sigh of
relief once the initial cost of getting new tooling in had been
overcome.
(having said that, Whitworth threads are, I'm told, still used in cases
where maximum strength is needed, such as some of the big threads in
bridges)
Me? I *like* working with points, *but* the problem is that the point
is ill-defined. Are we talking about Didot points? English/American
points? PostScript points? They're all different sizes, therefore the
point is a bad unit to use, as was the inch way back when before it was
given a global standard size.
[snip]
> > Japanese typesetters use the unit Q (quarter) for font sizes, where
> > 1 Q = 0.25 mm, i.e. the same modulus recommended by DIN
> > 16507-2.
>
> Which clearly suggests that either the mm unit or the base 10 is
> ill-suited for this particular application.
Base 10 is unsuitable for a lot of things.
[snip]
> The meter is now defined, retroactively, as the distance light travels
> through a vacuum in 1/299,792,458 of a second. That's inconsistent
> with the fundamental premises of the metric system in two ways: it's
> not a power of 10, and it's defined in relation to time units which
> are themselves base 12/base 60.
The time unit concerned is a second, nothing else. That in turn is
defined as a particular number of atomic transitions between a pair of
excitations states of a particular atom (IIRC).
The problem is that all units boil down to awkward stuff like this -
there's no `natural' unit of time, length, or even mass. If there's no
`natural' unit of those quantities, why try and impose any sort of
*anything* on a system of units?
There is nothing in the metric system which says that the basic units
need to be anything particularly logical.
> (As a matter of fact if you change the
> ratio to the nearest power of 10: 1/1,000,000,000, then the natural
> human-scale unit of distance according to the original principles of
> the metric system turns out to be 11.8028 inches, or pretty darn close
> to *one foot*.)
>
> A counter-argument will doubtless be that the metric system is by
> now too widely accepted to permit change in the defined length of a
> meter. "Change would be too costly." But this argument is equally
> valid as a reason *not* to switch to the metric system for anyone that
> has not switched yet. Such as typographers.
The main advantage of the metric system is that it's the only system of
measurement that is accepted globally. There's obvious advantages to
using metric whenever practical, but then again, I like miles and feet
and inches and all that stuff.
The thing that needs to be avoided is the horrible practice in the USA
of *mixing* units - for example, surface measurements on ICs being
referred to in `mils' (1/1000 inch or `thou' in real money) with depths
being specified in metric units. That kind of thing is sheer insanity.
> There is also some sentiment that the use of a decimal system of
> numbers is archaic and ill-founded (since 10 is divisible only by 2
> and 5),
AFAIK, you can't call base ten numbering archaic, because it's more
modern than base 12 and 60.
> and that the base-12/base-60 system used for our time units
> and units of angular measurement is mathematically speaking a better
> choice.
Mathematically speaking, it doesn't matter a damn which numbering system
you use, barring the point that it's usually easier to get a human or
computer to handle the numbering system if it uses a single base, so
time, which uses base 60 and base 12, is pretty silly (neither 60, 12,
nor 10 fits particularly neatly into the binary system used by almost
all computers). Equally, the imperial system of measuring length, using
base 12 (inches to a foot), base 3 (feet to a yard), base 22 (yards to a
chain), base 10 (chains to a furlong), and base 8 (furlongs to a mile),
is even more daft.
>So, to have 12 points per pica and 12 inches per foot may not
> be such a bad idea after all.
Rowland.
George Jefferson
:length in SI is the meter. Therefore, the product of two lengths
:must have units of meter squared--a coherent system requires that
:(the meter squared) to be _the_ unit of area, not 100 of them.
:Therefore, the "are" has been removed from the metric system, as
:defined in SI, now the official definition.
absolutely!. Let us know when they do away with the liter.
--
george jefferson : geo...@sol1.lrsm.upenn.edu
to reply simply press "r"
-- I hate editing addresses more than I hate the spam!
H. Peter Anvin
By author: jher...@ix.netcom.com(Joseph Hertzlinger)
In newsgroup: comp.std.internat
You mean duodecimal, don't you?
-hpa
--
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I am Bahá'í -- ask me about it or see http://www.bahai.org/
"To love another person is to see the face of God." -- Les Misérables
Martin Bailey
>By the way:
>Paper A4-size should have sidelengths of 0.2102241038134m and
>02973017787507m to get to the suppossed 0.0625 (1/16) sqmeters.
>
>But it's usually sold 0.21x0.297 which results in 0.6237 sqmeters, which
>is -0.208% off (that's the where the paper producers make their living
>of).
I don't know if they are based on an ISO standard, but the BSI
(British Standards Institute) specifications for A sizes find each
successively smaller size by dividing one dimension by two and
rounding to the nearest half mm.
Regards
Martin Bailey
----------------------------------------------------------
Digital Print & Publishing Harlequin Ltd
mar...@harlequin.com http://www.harlequin.com
----------------------------------------------------------
I try to ensure that my views expressed here accord with
my employers, but I am not a spokesman for Harlequin and
the buck stops with me for what I say here
----------------------------------------------------------
am...@nsof.co.il-n0spam
>The problem is that all units boil down to awkward stuff like this -
>there's no `natural' unit of time, length, or even mass.
Yes there are. Time and length are tied by the speed of light c; both
are tied to energy by Planck's constant h; and energy is tied to mass by
the gravitational constant G.
A units system in which all these constants are defined as 1 is the
"natural" one. However, it's not very useful: the basic units come up as
(If I did the computation correctly) 4.E-35 meter, 1.35E-43 sec and
5.46E-5 gram.
Victor Lua~na
: Who cares about the benefits to trade? The metric system is a Good
: Thing because it's a consistent international standard, and it was
True.
: The problem is that all units boil down to awkward stuff like this -
: there's no `natural' unit of time, length, or even mass. If there's no
: `natural' unit of those quantities, why try and impose any sort of
: *anything* on a system of units?
Not exactly true. The atomic unit system is internally consistent like the
SI, but is enterely based on fundamental constants of Nature. Customarily
all atomic and molecular calculations are done in atomic units to avoid
any worrying on unit conversions and the final results are then converted
to whatever SI or historical units happens to be commonly used at a
particular field. The atomic units are not, however, the only possible
system defined from fundamental constants alone.
--
HomePage %%http://www3.uniovi.es/~quimica.fisica/qcg/vlc/luana.html%%
+----------------------------------------------+ +---^---/ /
! Victor Lua~na ! | ~ / Just in case
! Departamento de Quimica Fisica y Analitica ! | | you don't
! Universidad de Oviedo, 33006-Oviedo, Spain ! < / remember
! e-mail: %%vic...@carbono.quimica.uniovi.es%% ! | / where Oviedo
! phone: (34)-8-5103491 fax: (34)-8-5103125 ! |____ ___/ is ;-)
+----------------------------------------------+ \/
Jeroen Teitsma
>
> > :As an example, area is the product of two lengths. _The_ unit of
> > :length in SI is the meter. Therefore, the product of two lengths
> > :must have units of meter squared--a coherent system requires that
> > :(the meter squared) to be _the_ unit of area, not 100 of them.
> > :Therefore, the "are" has been removed from the metric system, as
> > :defined in SI, now the official definition.
> >
>
>
> And a ml is a cubic centimeter. Oops!
>
>
>
>
And some unit are interlinked ( 1 A is the current needed to get 1 N force between to conducters of infinite length that are 1 m apart isn't it?)
Markus Kuhn
|> 022034...@t-online.de (Andreas Berghauer) wrote:
|> >Paper A4-size should have sidelengths of 0.2102241038134m and
|> >02973017787507m to get to the suppossed 0.0625 (1/16) sqmeters.
|> >
|> >But it's usually sold 0.21x0.297 which results in 0.6237 sqmeters, which
|> >is -0.208% off (that's the where the paper producers make their living
|> >of).
|>
|> I don't know if they are based on an ISO standard, but the BSI
|> (British Standards Institute) specifications for A sizes find each
|> successively smaller size by dividing one dimension by two and
|> rounding to the nearest half mm.
The ISO tolerance for the A4 format is ą2 mm anyway, so who
cares about the rounding of up to 0.5 mm?
More interesting details on A4 & friends:
http://www.cl.cam.ac.uk/~mgk25/iso-paper.html
George Jefferson
:But isn't the liter OK, because it is a thousand ml :-)?
:
:And a ml is a cubic centimeter. Oops!
it is "ok" in that it works, but it is an inconsistancy in the system
for the base named unit to be something other than m^3. Likewise
the 'base' force being N=Kg-m/s is inconsistant. Believe me these
things mess up the freshman engineering students just as much as
remembering factors of 12 or 5280.
Paul L. Allen
real-addr...@flur.bltigibbet (Rebecca and Rowland) writes:
> (having said that, Whitworth threads are, I'm told, still used in cases
> where maximum strength is needed, such as some of the big threads in
> bridges)
When we switched to metric it made sense to standardize on metric thread
sizes instead of the mix of BA, BSF, BSW, UNC, UNF and like. But the
cretins who designed the metric threads chose a sawtooth thread profile
instead of the sinusoidal profile typical of other threads. The sawtooth
profile concentrates stress in the thread root and leads to stress fatigue
more easily.
--Paul
Howard W. LUDWIG
George Jefferson wrote:> :As an example, area is the product of two lengths. _The_ unit of
> :length in SI is the meter. Therefore, the product of two lengths
> :must have units of meter squared--a coherent system requires that
> :(the meter squared) to be _the_ unit of area, not 100 of them.
> :Therefore, the "are" has been removed from the metric system, as
> :defined in SI, now the official definition.
>
> absolutely!. Let us know when they do away with the liter.
But isn't the liter OK, because it is a thousand ml :-)?
And a ml is a cubic centimeter. Oops!
No, the liter is not part of SI, so in that sense, it has been
done away with. _The_ unit of volume in SI is the meter cubed
since volume is just the product of three lengths (one for each
of the three dimensions of space), and meter (not centimeter) is
_the_ unit of length. There is no special name presently
accepted for that unit; the stere was once authorized, became
used almost exclusively for firewood, and now is deprecated.
One can, of course, use the cube of a multiple or submultiple
of the meter (such as millimeter cubed).
However, it must be recognized that liter was considered one of
the foundational units when the metric system was first legislated
in the 1790s in France. The liter did become very popular
in
everyday, general public usage and commerce as well as in scientific
writings as a unit of volume for liquids and gases.
Because of its ingrained popularity in "metricized" countries,
the General Committee of Weights and Measures (CGPM, French
acronym) has accepted (as a matter of practicality, not ideality)
the continued use of liter in the same context as SI units.
However, CGPM also strongly recommends that the liter _not_ be
used for precise scientific measures, because the definition of
the liter was changed in 1964 with an impact of about 28 parts
per million and there can be confusion regarding which definition
(size) is intended.
Howard W. LUDWIG, Ph.D.
Howard W. LUDWIG
George Jefferson wrote:
:
:But isn't the liter OK, because it is a thousand ml :-)?
:
:And a ml is a cubic centimeter. Oops!
:it is "ok" in that it works, but it is an inconsistancy in the system
for the base named unit to be something other than m^3. Likewise
the 'base' force being N=Kg-m/s is inconsistant. Believe me these
things mess up the freshman engineering students just as much as
remembering factors of 12 or 5280.--
george jefferson : geo...@sol1.lrsm.upenn.edu
system. There is no base unit for volume, as volume is derived
from the base quantity length, specifically the volume is the
cube of length. Since the unit of length is the meter, the unit
of volume is the meter cubed. The liter, being 0.001 m^3, is
thus not the unit of volume in SI, contrary to common opinion.
As I note in another reply, the Committee on Weights and Measures
(CGPM, French acronym) recognizes the popularity of the liter
(which was one of the foundational units of the metric system as
originally defined) and (out of practicality rather than ideality)
permits the liter to be used in the same context as SI, without
admitting the liter as part of SI. However, CGPM also discourages
the use of liter in documenting precise measurements because the
definition of liter was changed by about 28 parts per million in
1964, and there could easily be confusion about which definition
(size) was used.
There is _no_ inconsistency in the unit of force being a newton.
The unit of force is _not_ a base unit, but rather derived from
the base units meter (for length), kilogram (mass), and second
(time). Force is mass times acceleration and acceleration
is
length divided by time-squared. To have coherency of units,
the unit of force must thus be kg*m/s^2, which has been given
the special name of newton (symbol N). [The square on time
was
left out of the above post.] What is inconsistent about this?
The only peculiar thing about SI (and perhaps this is what is
causing the confusion regarding force for your classes) is that
the base quantity mass has as its unit the kilogram (kg), a name
and symbol with a prefix built in. Multiples and submultiples
replace the prefix, rather than prepend another prefix.
It would help to refer to web sites at BIPM or NIST to understand
the meaning of base and derived units in a coherent system and
use
of SI. (URLs provided in earlier post.)
Howard W. LUDWIG, Ph.D.
D. Henkel-Wallace
From: am...@nsof.co.il-n0spam
>The problem is that all units boil down to awkward stuff like this
>- there's no `natural' unit of time, length, or even mass.
Yes there are. Time and length are tied by the speed of light c;
both are tied to energy by Planck's constant h; and energy is tied
to mass by the gravitational constant G.
I'm afraid it's not as simple as you say. Yes, c helps us define
distance and time fairly prceisely, and allows "anybody" to accurately
generate copies of reference values. But the same is not true of
mass.
The kilogram is still defined as precisely the mass of a specific
sample (prototype) of platinum kept in Sevres (ref:
http://physics.nist.gov/cuu/Units/kilogram.html).
I hope that someday someone will provide an "open source" of the
fundamental unit of mass. Until then, it's no better than the length
of a king's nose.
d
gumby at henkel-wallace point org
PS: The NIST defines the second differently from how it was referred
to in this thread: http://physics.nist.gov/cuu/Units/second.html
George Jefferson
:and symbol with a prefix built in.
ah, not inconsistant just peculiar <g>.
I suppose the committe had some good reasons.
Louis Vosloo
Louis Vosloo wrote:George Jefferson wrote:No, the liter is not part of SI, so in that sense, it has been> :As an example, area is the product of two lengths. _The_ unit of
> :length in SI is the meter. Therefore, the product of two lengths
> :must have units of meter squared--a coherent system requires that
> :(the meter squared) to be _the_ unit of area, not 100 of them.
> :Therefore, the "are" has been removed from the metric system, as
> :defined in SI, now the official definition.
>
> absolutely!. Let us know when they do away with the liter.But isn't the liter OK, because it is a thousand ml :-)?
And a ml is a cubic centimeter. Oops!
done away with. _The_ unit of volume in SI is the meter cubed
are "SI clean" but continue to use odd units like km/hour, Angstrom, are, litre.
Joseph Hertzlinger
Anvin) writes:
>You mean duodecimal, don't you?
The term "duodecimal" (two plus ten) is based on the idea that twelve
is important only in relation to ten. The term "dozenal" is based on
the idea that twelve is important in itself.
Nick Sweeney
> Besides, the US switched to the metric system years ago. Congress has passed
> several laws in this regard over the past two centuries (way before the Brits).
> Jefferson brought such revolutionary ideas back from Paris (where he apparently
> was distracted by more than revolutionary ideas).
I notice that the US was pretty quick to abandon the Imperial
measurement of wealth; anthone fancy re-introducing the shilling for
consistency's sake?
Nick Sweeney
--
http://www.jesus.ox.ac.uk/~nsweeney/head/
"A letter always arrives at its destination." - Jacques Lacan
Dave Fawthrop
In article <36A6793C...@lmco.com>, "Howard W. LUDWIG" (howard....@lmco.com) writes:
>Rodger Whitlock wrote:
>
<big snip>
>
>Some people complain about the number (20) of prefixes to remembernow in SI,
>and most of them are separated by factors of 1000, not
>10.
>
<big snip>
There reason for the factors of 1000 in SI units is,
*************saving.lives**************************
SI units are used in pharmacology where the diference between the
theraputic dose and the lethal dose is often small, and less than
a factor of 10.
Poeple make mistakes but a mistake but a factor of 1000 is obvious.
A mistake by a factor of 10 is easy to miss.
*Do* *not* *under* *any* *circumstanses* *take* *ten* *times* *the*
*theraputic* *dose* *of* *paracetamol* the second most common
painkiller used in the UK.
Without *immediate* medical care you have condemned yourself to
*****cirtain**** and ****most**** *****unpleasant**** ****death****
-- Dave Fawthrop <hyp...@c-h.win-uk.net> <http://www.win-uk.net/~hyphen>
Computer Hyphenation Ltd, Hyphen House, 8 Cooper Grove, Halifax HX3 7RF, UK
Tel/Fax/Answer +44 (0)1274 691092.
Hyphenologist is sold as C source code and splits 50 languages.
Wordlist FAQ at http://www.win-uk.net/~hyphen/wordlist.html
VDU Glasses at http://www.win-uk.net/~hyphen/vduglasses.html
Pete Forman
Joseph> In <78673k$tg0$1...@palladium.transmeta.com>
Joseph> h...@transmeta.com (H. Peter Anvin) writes:
>> You mean duodecimal, don't you?
Joseph> The term "duodecimal" (two plus ten) is based on the idea
Joseph> that twelve is important only in relation to ten. The term
Joseph> "dozenal" is based on the idea that twelve is important in
Joseph> itself.
But "dozen" ultimately came from the Latin "duodecim" by way of the
Old French "dozeine". Even "twelve" probably came from "[ten and] two
left".
--
Pete Forman
Western Geophysical
pete....@westgeo.com
Gernot Katzer
>
> real-addr...@flur.bltigibbet (Rebecca and Rowland) writes:
>
> >there's no `natural' unit of time, length, or even mass.
>
> are tied to energy by Planck's constant h; and energy is tied to mass by
> the gravitational constant G.
>
> "natural" one.
No, it's not. There are far too many natural constants which one
would like to set equal to one, and there are even dependencies
which one cannot ignore.
As a quantum chemist, I conveniently use a system in which electron
mass, electron charge, Bohr's radius and Planck's constant are all set
equal to unity. For those doing relativistic calculations, it would be
nice to have the speed of light also removed ... but nature won't allow.
Other disciplines will want another subset of natural constants
to vanish from their formulae, but you can't create a general system
like this that satisfies all needs, even if you are willing to
work with scales incnvenient for everyday usage.
Gernot
Rebecca and Rowland
>
> In article <36A6793C...@lmco.com>, "Howard W. LUDWIG"
(howard....@lmco.com) writes:
> >Rodger Whitlock wrote:
> >
>
> <big snip>
>
> >
> >Some people complain about the number (20) of prefixes to remembernow in SI,
> >and most of them are separated by factors of 1000, not
> >10.
Well... Virtually no-one needs to use more than half of the prefixes,
do they? How many people *really* use Tera *and* atto on a regular
basis? And have you *ever* seen yocto used for anything?
(on top of that, I bet most people don't even realise they're using a
multiplicative prefix when they say `kilometre' or `centimetre')
> <big snip>
>
> There reason for the factors of 1000 in SI units is,
>
> *************saving.lives**************************
>
> SI units are used in pharmacology where the diference between the
> theraputic dose and the lethal dose is often small, and less than
> a factor of 10.
The metric prefixes were developed, AFAIK, quite independently of
pharmacology.
[snip]
Harald Hanche-Olsen
| Well... Virtually no-one needs to use more than half of the prefixes,
| do they? How many people *really* use Tera *and* atto on a regular
| basis? And have you *ever* seen yocto used for anything?
Well, at least the tera is not *that* unkommon a prefix: The annual
(electric) energy cosumption of a country like Norway is typically
quoted to be around 100 TWh. Of, course, an SI purist would like to
say 360 PJ instead. (And the annual worldwide emissions of CO2,
usually measured in billion tons (American billions, i.e. Gt) should
really be measured in Pg instead.)
If you're an astronomer *and* an SI purist you would probably abandon
the light-year, which is really a bit short of 10 Pm, if my
calculation is correct. Which would make the Milky way about 1 Zm
across. For intergalactic distances, even the Ym seems too short to
really be of much use. 8-)
I have never seen the atto prefix used for anything, but I remember
reading a report on the numerical simulation of a quark-gluon plasma
that used one femtometer (fm) for its typical length scale.
Surely, an attosecond is way too long a time to be usable in this
context, if things happen at relativistic speeds.
ObWarning: I don't suppose aviators will ever stop using nautical
miles for horizontal and feet for vertical distances. The death toll
from the inevitable chaos reigning during the transition period would
just not be acceptable. But I cannot think of any other areas where
the introduction of the metric system would be so obviously
disastrous. Except perhaps one: If the British were forced to drink
their beer in half liters, there would probably be a revolution.
--
* Harald Hanche-Olsen <URL:http://www.math.ntnu.no/~hanche/>
- «There arises from a bad and unapt formation of words
a wonderful obstruction to the mind.» - Francis Bacon
Tor Arntsen
Harald Hanche-Olsen <han...@math.ntnu.no> writes:
>ObWarning: I don't suppose aviators will ever stop using nautical
>miles for horizontal and feet for vertical distances. The death toll
There is no real need to use feet for anything, however nautical miles
are very nice because one nautical mile = one (normalised) latitude-minute.
This is way off-topic though!
- Tor
Roy Smith
> I have never seen the atto prefix used for anything
I remember once getting a schematic which had a 10nF capacitor marked on
it. Now, while there is nothing really wrong with nF (nano-farad) as a
unit of capacitance, it's never used. Capacitors are either uF or pF.
Just the way it is, and no fancy-schmancy SI-puke gonna change it! A 10
nF capacitor would be marked .01 uF by any rational person. The notation
was so bizarre, I ended up tracking down the original circuit designer to
ask him what he really meant.
> ObWarning: I don't suppose aviators will ever stop using nautical
> miles for horizontal and feet for vertical distances. The death toll
> from the inevitable chaos reigning during the transition period would
> just not be acceptable.
I believe the Russians, and a few other countries too, use meters for
altitudes. This does have the potential to cause some confusion. There
was a crash a few years back in India in which a mis-conversion between
meters and feet was cited as a contributing cause.
> But I cannot think of any other areas where the introduction of the
> metric system would be so obviously disastrous.
There would be some pain during the transition, but I think "obviously
disasterous" is a bit overstated.
Joseph Hertzlinger
<gse...@compo.bedford.waii.com> writes:
>But "dozen" ultimately came from the Latin "duodecim" by way of the
>Old French "dozeine". Even "twelve" probably came from "[ten and] two
>left".
In that case, we should ask the nearest extraterrestrial what the
appropriate term is. Why should we stick to international standards
instead of interstellar?
OTOH, maybe we should use binary.
Paul Keinanen
Smith) wrote:
: Harald Hanche-Olsen <han...@math.ntnu.no> wrote:
: > I have never seen the atto prefix used for anything
: I remember once getting a schematic which had a 10nF capacitor marked on
: it. Now, while there is nothing really wrong with nF (nano-farad) as a
: unit of capacitance, it's never used. Capacitors are either uF or pF.
: Just the way it is, and no fancy-schmancy SI-puke gonna change it! A 10
: nF capacitor would be marked .01 uF by any rational person. The notation
: was so bizarre, I ended up tracking down the original circuit designer to
: ask him what he really meant.
That may apply to some backward people in the US, but in Europe it
perfectly common to use nanofarads. In schematic diagrams it is also
common to replace the decimal separator (point or comma) with the
prefix and omit the unit completely (since everyone reading schematic
diagrams should know that capacitors are measured in Farads and not
Ohms etc.), e.g. 2n7 is 2.7 nF.
BTW, the femto- prefix has been used in the USA for quite a while in
FM broadcast receiver sensitivity specifications. The required
received signal is specified in dBf, which is decibels relative to 1
fW or 1E-15W. For a usable mono reception, about 10 fW is required.
: I believe the Russians, and a few other countries too, use meters for
: altitudes. This does have the potential to cause some confusion.
At least the METAR meteorological telegram for St. Petersburg
international airport specified cloud levels in feet, but the wind
speed in m/s, while other countries use knots. I do not know what the
situation inside Russia is today. Estonia, which regained independence
from Soviet Union for nearly a decade ago, first used m/s for wind
speed but has gone to knots in METAR telegrams.
: There would be some pain during the transition, but I think "obviously
: disasterous" is a bit overstated.
There was a near miss in Canada with the famous Gimli incident, in
which a passenger jet liner was incorrectly fueled by the ground crew
in pounds, while the fuel consumption was calculated in kilograms. The
fuel ran out in mid flight, but the plane made a successful unpowered
landing on the deserted Gimli air strip, thanks to the glider
experience of one of the pilots. Later simulator tests showed that
most regular air liner crews would have crashed the plane in the same
situation.
Eric Bohlman
: Harald Hanche-Olsen <han...@math.ntnu.no> wrote:
: > I have never seen the atto prefix used for anything
: I remember once getting a schematic which had a 10nF capacitor marked on
: it. Now, while there is nothing really wrong with nF (nano-farad) as a
: unit of capacitance, it's never used. Capacitors are either uF or pF.
: Just the way it is, and no fancy-schmancy SI-puke gonna change it! A 10
: nF capacitor would be marked .01 uF by any rational person. The notation
: was so bizarre, I ended up tracking down the original circuit designer to
: ask him what he really meant.
IME, the use of nanofarads to designate capacitor values is extremely
common in the UK.
Rebecca and Rowland
> Harald Hanche-Olsen <han...@math.ntnu.no> wrote:
> > I have never seen the atto prefix used for anything
>
> I remember once getting a schematic which had a 10nF capacitor marked on
> it. Now, while there is nothing really wrong with nF (nano-farad) as a
> unit of capacitance, it's never used. Capacitors are either uF or pF.
> Just the way it is, and no fancy-schmancy SI-puke gonna change it! A 10
> nF capacitor would be marked .01 uF by any rational person. The notation
> was so bizarre, I ended up tracking down the original circuit designer to
> ask him what he really meant.
How odd. If I need a 10nF capacitor, I say 10nF. If the damned thing
is marked in puffs, then so be it - it's hardly rational, though.
It's so much more convenient than using older, irrational units like
`jars', or rational but extinct units like `centimetres' for
capacitance. I've never really understood why people think that writing
0.001 uF or 1000 pF is easier than saying 1 nF.
[snip]
> > But I cannot think of any other areas where the introduction of the
> > metric system would be so obviously disastrous.
>
> There would be some pain during the transition, but I think "obviously
> disasterous" is a bit overstated.
How else would you describe the loss of thousands of lives due to
avoidable air crashes?
Roy Smith
> There was a near miss in Canada with the famous Gimli incident, in
> which a passenger jet liner was incorrectly fueled by the ground crew
> in pounds, while the fuel consumption was calculated in kilograms.
To blame the Gimli Glider incident on a metric conversion error alone
would be stretching it. There were a whole bunch of events which chained
together (as is often the case) with the pound/kg conversion error. For
example, the fuel gauges in the cockpit were broken. Anyway, that's
rather a bad example. We were talking about altitudes in feet vs.
meters. Measuring fuel loads in pounds vs kg has little to do with
measuring altitudes in feet.
The medical world made the transition from english to metric with no
problems, I don't see any reason why the aviation world couldn't.
Markus Kuhn
|> kein...@sci.fi (Paul Keinanen) wrote:
|> > There was a near miss in Canada with the famous Gimli incident, in
|> > which a passenger jet liner was incorrectly fueled by the ground crew
|> > in pounds, while the fuel consumption was calculated in kilograms.
|>
|> To blame the Gimli Glider incident on a metric conversion error alone
|> would be stretching it. There were a whole bunch of events which chained
|> together (as is often the case) with the pound/kg conversion error. For
|> example, the fuel gauges in the cockpit were broken. Anyway, that's
|> rather a bad example. We were talking about altitudes in feet vs.
|> meters. Measuring fuel loads in pounds vs kg has little to do with
|> measuring altitudes in feet.
There was also the crash of a Russian transporter in India a few years
ago, where the conversion between altitude meters and feet that
has to be done by every Russian crew in countries with non-metric air
traffic control was considered to be one element in the usual long list
of things that went wrong simultaneously.
|> The medical world made the transition from english to metric with no
|> problems, I don't see any reason why the aviation world couldn't.
Exactly.
Actually, considering that there are huge regions on this planet including
Russia and (I think) China doing metric air traffic control, the real
hazards are created by NOT switching to the metric system and still
keeping the US Flintstone units alive in Western aviation.
If there is a well-planned coordinated initiative to switch over Western
air traffic control on a fixed day, say 1 January 2003 to altitude in
meters, cargo load and fuel in kg, etc., there should certainly no
risks be associated with that. Cockpit instrument scales/software would
be exchanged/reconfigured over night during normal plane servicing, for
a few days, altitudes would be reported in both meters and feet to allow
everyone to catch on, and after two or three weeks, every professional
pilot will have gotten completely used to the new system. Pilots constantly
have to get familiar with new regulations and changing conditions at
various airports. Getting used to a new altitude units is trivial stuff
for someone working in such a naturally dynamic and excellently
trained job environment.
It is amazing to what length some US folks go to create irrational
justifications for keeping their bizarre archaic system of units
alive, no matter whether it is in aviation or typography.
Sven Utcke
> Harald Hanche-Olsen <han...@math.ntnu.no> wrote:
> > ObWarning: I don't suppose aviators will ever stop using nautical
> > miles for horizontal and feet for vertical distances. The death toll
> > from the inevitable chaos reigning during the transition period would
> > just not be acceptable.
>
> I believe the Russians, and a few other countries too, use meters for
> altitudes.
German gliders use meters for altitude and km/h for speed. Commercial
aviation doesn't, though.
Sven
--
_ _ Lehrstuhl fuer Mustererkennung und Bildverarbeitung
| |_ __ | |__ Sven Utcke
| | ' \| '_ \ phone: +49 761 203 8274 Am Flughafen 17
|_|_|_|_|_.__/ fax : +49 761 203 8262 79110 Freiburg i. Brsg.
mailto:ut...@informatik.uni-freiburg.de www.informatik.uni-freiburg.de/~utcke
Tor Arntsen
r...@popmail.med.nyu.edu (Roy Smith) writes:
>I remember once getting a schematic which had a 10nF capacitor marked on
>it. Now, while there is nothing really wrong with nF (nano-farad) as a
>unit of capacitance, it's never used. Capacitors are either uF or pF.
>Just the way it is, and no fancy-schmancy SI-puke gonna change it! A 10
>nF capacitor would be marked .01 uF by any rational person. The notation
>was so bizarre, I ended up tracking down the original circuit designer to
>ask him what he really meant.
As somebody else said, maybe that's some US thing? Sounds really
strange to me though, as nanofarad is totally familiar to me. I've
seen enough US schematics but maybe I just haven't noticed that there
weren't any nF there..?
- Tor (electronics engineer)
Stephan I. Boettcher
> It's so much more convenient than using older, irrational units like
> `jars', or rational but extinct units like `centimetres' for
> capacitance. I've never really understood why people think that writing
> 0.001 uF or 1000 pF is easier than saying 1 nF.
On the actual device it's usually either uF or pF, without the F,
and often without the n or p. Knowing the type and size of the
capacitor allows to decide if it's pF or uF. Not so if you have to
consider nF as well.
Stephan
--
------------------------------------------------------------------------
Stephan Boettcher FAX: +1-914-591-4540
Columbia University, Nevis Labs Tel: +1-914-591-2863
P.O. Box 137, 136 South Broadway mailto:ste...@nevis1.columbia.edu
Irvington, NY 10533, USA http://www.nevis.columbia.edu/~stephan
------------------------------------------------------------------------
Rebecca and Rowland
> In article <roy-240199...@mcsv29-p3.med.nyu.edu>,
r...@popmail.med.nyu.edu (Roy Smith) writes:
[snip]
> |> The medical world made the transition from english to metric with no
> |> problems, I don't see any reason why the aviation world couldn't.
>
> Exactly.
I can think of one reason: the medical world *didn't* make the
transition with no problems. Lots of mistakes were made.
> Actually, considering that there are huge regions on this planet including
> Russia and (I think) China doing metric air traffic control, the real
> hazards are created by NOT switching to the metric system and still
> keeping the US Flintstone units alive in Western aviation.
The units are imperial units that date back to the empire - the Roman
empire, that is. They're not US units; nor are they English units.
> If there is a well-planned coordinated initiative to switch over Western
> air traffic control on a fixed day, say 1 January 2003 to altitude in
> meters, cargo load and fuel in kg, etc., there should certainly no
> risks be associated with that. Cockpit instrument scales/software would
> be exchanged/reconfigured over night during normal plane servicing,
<cough> And just where do you think you're going to find the staff to
do that?
>for
> a few days, altitudes would be reported in both meters and feet to allow
> everyone to catch on, and after two or three weeks, every professional
> pilot will have gotten completely used to the new system. Pilots constantly
> have to get familiar with new regulations and changing conditions at
> various airports. Getting used to a new altitude units is trivial stuff
> for someone working in such a naturally dynamic and excellently
> trained job environment.
Umm... I'd not say it was trivial myself. All pilots would have to
have simulator training to get used to the new units. How do you
arrange for the instruments to display both feet and metres `for a few
days', and then suddenly stop?
> It is amazing to what length some US folks go to create irrational
> justifications for keeping their bizarre archaic system of units
> alive, no matter whether it is in aviation or typography.
Oi! It's not the USA's system of units (aside from their stupid pints,
of course). It's the imperial system of units, dating from the Roman
empire.
Rebecca and Rowland
> real-addr...@flur.bltigibbet (Rebecca and Rowland) writes:
>
> > It's so much more convenient than using older, irrational units like
> > `jars', or rational but extinct units like `centimetres' for
> > capacitance. I've never really understood why people think that writing
> > 0.001 uF or 1000 pF is easier than saying 1 nF.
>
> On the actual device it's usually either uF or pF, without the F,
> and often without the n or p. Knowing the type and size of the
> capacitor allows to decide if it's pF or uF. Not so if you have to
> consider nF as well.
That's a good reason for choosing that way of marking the *device*.
It's not a good reason for writing it that way on a circuit diagram
IMHO.
Paul L. Allen
t...@spacetec.no (Tor Arntsen) writes:
> In article <roy-230199...@mcsv45-p10.med.nyu.edu>,
> r...@popmail.med.nyu.edu (Roy Smith) writes:
> >I remember once getting a schematic which had a 10nF capacitor marked on
> >it. Now, while there is nothing really wrong with nF (nano-farad) as a
> >unit of capacitance, it's never used. Capacitors are either uF or pF.
> >Just the way it is, and no fancy-schmancy SI-puke gonna change it! A 10
> >nF capacitor would be marked .01 uF by any rational person. The notation
> >was so bizarre, I ended up tracking down the original circuit designer to
> >ask him what he really meant.
>
> As somebody else said, maybe that's some US thing? Sounds really
> strange to me though, as nanofarad is totally familiar to me. I've
> seen enough US schematics but maybe I just haven't noticed that there
> weren't any nF there..?
Decimal points are small things and easily missed. They can get erased
on drawings and rubbed off components. Dirt marks on drawings can look
like decimal points. There's a big difference between 1uF and .1uF
(zeroes to the left of the point are often omitted on components to
save space). Using 2n7 rather than 0.027uF is a recognized convention
(enshrined in an ISO standard somewhere). We also use 3R9 here because
on hand-lettered drawings it's all too easy to lose or acquire a decimal
point by accident.
This has only been going on for the past 30 years or so...
--Paul
Peter Flynn
> There reason for the factors of 1000 in SI units is,
> *************saving.lives**************************
This is why (before the metric system was adopted in English-
speaking countries) pharmacists used special symbols for
drachms, scruples, ounces, etc. Unfortunately they too were
ill-chosen and subject to confusion...I possess a Pharmacopoeia
of 1864 where a handwritten conversion note about units on the
flyleaf has been crossed out by a subsequent owner with an irate
correction, which itself in turn has been crossed out by a later
owner with a similarly irate correction. At least both SGML and
TeX systems are capable of handling the unit symbols, assuming
the editor or author has typed them in correctly...
> *Do* *not* *under* *any* *circumstanses* *take* *ten* *times* *the*
> *theraputic* *dose* *of* *paracetamol* the second most common
> painkiller used in the UK.
[Off-topic: apologies] Do any of our medical users know why paracetamol
is unknown in the USA? They still use Aspirin over there!
///Peter
--
[followups edited]
DTDs are not common knowledge because programming students are not
taught markup. A markup language is not a programming language.
Peter Flynn
[aeronautics in feet or meters?]
> > But I cannot think of any other areas where the introduction of the
> > metric system would be so obviously disastrous.
>
> There would be some pain during the transition, but I think "obviously
> disasterous" is a bit overstated.
A bit like the proposal that we should change from driving on the left
to driving on the right...gradually? :-)
///Peter
--
Peter Kerr
>> `jars', or rational but extinct units like `centimetres' for
>> capacitance. I've never really understood why people think that writing
>> 0.001 uF or 1000 pF is easier than saying 1 nF.
>
>On the actual device it's usually either uF or pF, without the F,
>and often without the n or p. Knowing the type and size of the
>capacitor allows to decide if it's pF or uF. Not so if you have to
>consider nF as well.
>
And color coded capacitors?
Where the first two stripes give the two significant
figures of the size and the third gives the exponent as:
number of zeroes when expressed in pF? or
negative of the SI exponent?
I have seen both...
--
Peter Kerr bodger
School of Music chandler
University of Auckland New Zealand neo-Luddite
Richard Quint
says...
>
>
>[Off-topic: apologies] Do any of our medical users know why paracetamol
>is unknown in the USA? They still use Aspirin over there!
>
include Tylenol. Aspirin is often more effective for many people, and
buffered aspirin (almost impossible to get in the UK since the American
military presence has decreased) reduces the associated stomach upsets.
Paul Keinanen
: Harald Hanche-Olsen <han...@math.ntnu.no> wrote:
: > I have never seen the atto prefix used for anything
<feet vs. m in aviation>
: > But I cannot think of any other areas where the introduction of the
: > metric system would be so obviously disastrous.
: There would be some pain during the transition, but I think "obviously
: disasterous" is a bit overstated.
I am not a pilot, but as far as I understand, the altimeters are
simply barometers with the scale marked as "feet".
A plane maintaining flight level FL 330 = 33000 ft is actually
maintaining a barometric pressure of about 250 hPa. Since FL 0 is
still _defined_ as 1013.2 hPa, but the surface pressure varies and the
temperature of the air below the plane varies, the absolute altitude
(relative to the reference geoid or the mean sea level or whatever the
reference level might be) of the 250 hPa level varies depending on
location. So in reality, the altitude should not be expressed in
length units (neither feet or meter), thus, the FL is as good as any
other arbitrary unit.
For lower altitudes, the altitude displayed is actually the pressure
difference from the _measured_ runway barometric pressure, so this has
a better correlation with the true altitude and as such, it makes
sense to measure it in a length unit. With everything else in metric
units, sooner or later, the aviation industry is going to convert to
metric.
The aviation industry is also very conservative, for instance with
communication equipment. The radios are still AM, when everyone else
have converted to FM or digital for a long time ago.
Paul Keinanen
Boettcher) wrote:
: real-addr...@flur.bltigibbet (Rebecca and Rowland) writes:
: > It's so much more convenient than using older, irrational units like
: > `jars', or rational but extinct units like `centimetres' for
: > capacitance. I've never really understood why people think that writing
: > 0.001 uF or 1000 pF is easier than saying 1 nF.
: On the actual device it's usually either uF or pF, without the F,
: and often without the n or p. Knowing the type and size of the
: capacitor allows to decide if it's pF or uF. Not so if you have to
: consider nF as well.
Looking at the various capacitors in my inventory, specifying the
capacitance in microfarads is only common for capacitances greater
than 100 nF (0.1 uF). I could find only a few 0.022 uF capacitors.
Capacitors greater than 1 nF but less than 10 nF were either in pF or
nF (e.g. 1n5). In the 10 to 100 nF range, the nF notation was the most
common. Then there is the colour code system similar to resistors (but
with 1=1 pF) and a numeric form of this 470 = 47 pF, 471= 470 pF,
472=4.7 nF, 473=47 nF and so on. On chip capacitors, it was hard to
make sense of the part number anyway, so had to be careful not to mix
these devices into a single box or you had to measure the capacitance
of each.
Paul
Thorsten Ohl
Rebecca and Rowland write:
> How many people *really* use Tera *and* atto on a regular basis?
I do :-).
Tera as in TeV (that's 10^{12} electron Volts) for energies and atto
as in attobarn (that's 10^{-18}\cdot 10^{-10}cm^{-2}) for cross
sections.
Granted, we will have to wait another 10 years for the collider for
doing the corresponding physics ...
--
Thorsten Ohl, Physics Department, TU Darmstadt -- o...@hep.tu-darmstadt.de
http://heplix.ikp.physik.tu-darmstadt.de/~ohl/ [<=== PGP public key here]
Juergen von Hagen
>
> It would help to refer to web sites at BIPM or NIST to understand
> the meaning of base and derived units in a coherent system and use
> of SI. (URLs provided in earlier post.)
>
> Howard W. LUDWIG, Ph.D.
or read the SIunits package description for LaTeX. Marcel has done
a great work to conclude and descibe the whole system and the
implications
cheers
juergen
Chris Gooch
Nothing wrong with Newtons surely? Kilogrammes are the
unit of mass, Newtons are measurement of force (aka weight)
worked out as the derived unit kg m s^-2, from the dimensions
Mass times Acceleration, where obviously Acceleration is
Length per unit Time squared. F=ma is one of Newton's, hence the name.
the fact that weight and mass are then easily distinguished
by high school students, and the relation between them, g,
being therefore obvious, is surely handy. Using the SI system
clarifies this point for you - mass and weight are different
things. A 1kg mass weighs just under 10 Newtons on Earth (g being 9.83
I seem to remember), but only about 3 Newtons on the Moon.
Knowing this also enables you to remember that things fall at
about 3 metres per second squared - no need to remember another
constant such as 22 feet per second per second.
Being brought up on SI units enables many problems in engineering and
physics to be clarified by being able to comprehend the relation between
the dimensions which are inherent in the units of measurement used.
So 13 or 14 year old kids in Britain have no problem with any of this,
till they grow up and meet old fogeys at work, or try and understand the
weather forecasts on the BBC (I'm 29 and have never understood
Farenheit,
no one under 35 does in Britain, so why do they stick with it on the
telly?!)
BTW this nationalistic approach always gives me a chuckle -- British
readers
may remember Micheal Portillo (oddly enough half Spanish), a right wing
tory give a speach a few years ago about not wanting closer ties with
Europe,
invoking the spectre of the good old British Army having to become part
of
a European defence force and use kilometers and so on. It was later
pointed
out to him that the British armed forces, as well as even the Americans,
have
used metric units for a very long time. The reason: you don't want any
confusion
over distances if you're on the ground targetting an air strike.
Christopher Gooch, Technical Author,
LightWork Design Ltd., Sheffield, England.
(ch...@lightwork.co.uk) (www.lightwork.com)
-----Original Message-----
From: geo...@sol1.lrsm.upenn.edu ( George Jefferson )
[mailto:geo...@sol1.lrsm.upenn.edu]
Posted At: Thursday, January 21, 1999 6:51 PM
Posted To: comp.text.tex
Conversation: Metric Typographic Units and Font Sizes
Subject: Re: Metric Typographic Units and Font Sizes
:
:But isn't the liter OK, because it is a thousand ml :-)?
:
:And a ml is a cubic centimeter. Oops!
:
it is "ok" in that it works, but it is an inconsistancy in the system
for the base named unit to be something other than m^3. Likewise
the 'base' force being N=Kg-m/s is inconsistant. Believe me these
things mess up the freshman engineering students just as much as
remembering factors of 12 or 5280.
--
george jefferson : geo...@sol1.lrsm.upenn.edu
to reply simply press "r"
-- I hate editing addresses more than I hate the spam!
David Peterson
Gernot Katzer <KAT...@bkfug.kfunigraz.ac.at> wrote:
> am...@nsof.co.il-n0spam wrote:
> > A units system in which all these constants are defined as 1 is the
> > "natural" one.
>
> No, it's not. There are far too many natural constants which one
> would like to set equal to one, and there are even dependencies
> which one cannot ignore.
>
> As a quantum chemist, I conveniently use a system in which electron
> mass, electron charge, Bohr's radius and Planck's constant are all set
> equal to unity. For those doing relativistic calculations, it would be
> nice to have the speed of light also removed ... but nature won't allow.
I recall back in the '50s or '60s reading an interesting article
pointing out that our arbitrary choice of units pales when compared
to our arbitrary choice of dimensions. ("Arbitrary", of course, was
thought to be "inherent in the design of the universe" when the choices
were made.) The article pointed out how many important concepts wind
up with fractional powers of standard dimensions (you understand meters
squared; how about meters "square-rooted"?). And gave examples of
alternative dimensional choices, including one where not only could
the speed of light be 1, but it was *dimensionless*. Mass and energy
were the same dimension!
Dave Peterson
SGMLWorks!
H. Peter Anvin
By author: t...@spacetec.no (Tor Arntsen)
In newsgroup: comp.std.internat
>
> As somebody else said, maybe that's some US thing? Sounds really
> strange to me though, as nanofarad is totally familiar to me. I've
> seen enough US schematics but maybe I just haven't noticed that there
> weren't any nF there..?
>
Yes, I was somewhat surprised to find when I moved from Europe to the
U.S. that engineers here don't use nF. I consider it to be another
manifestation of the U.S. being reluctant to adopt new units (whereas
they still use things like "microinches"...)
-hpa
--
PGP: 2047/2A960705 BA 03 D3 2C 14 A8 A8 BD 1E DF FE 69 EE 35 BD 74
See http://www.zytor.com/~hpa/ for web page and full PGP public key
I am Bahá'í -- ask me about it or see http://www.bahai.org/
"To love another person is to see the face of God." -- Les Misérables
H. Peter Anvin
By author: kein...@sci.fi (Paul Keinanen)
In newsgroup: comp.std.internat
>
> I am not a pilot, but as far as I understand, the altimeters are
> simply barometers with the scale marked as "feet".
>
> A plane maintaining flight level FL 330 = 33000 ft is actually
> maintaining a barometric pressure of about 250 hPa. Since FL 0 is
> still _defined_ as 1013.2 hPa, but the surface pressure varies and the
> temperature of the air below the plane varies, the absolute altitude
> (relative to the reference geoid or the mean sea level or whatever the
> reference level might be) of the 250 hPa level varies depending on
> location. So in reality, the altitude should not be expressed in
> length units (neither feet or meter), thus, the FL is as good as any
> other arbitrary unit.
There is nothing wrong with using a length unit here; it is equivalent
altitude for a specific pressure, and is measured in length units.
Since that is what you care about for spacing, etc, it makes good sense.
> For lower altitudes, the altitude displayed is actually the pressure
> difference from the _measured_ runway barometric pressure, so this has
> a better correlation with the true altitude and as such, it makes
> sense to measure it in a length unit. With everything else in metric
> units, sooner or later, the aviation industry is going to convert to
> metric.
I think the main change-inducing factor is going to be GPS/GLONASS;
with satnav as primary position indicator, a lot of the kluges used in
aviation today are going to be exposed as just that -- kluges -- since
satnav measures true position no matter what, and the airspace system
is going to have to adjust with it. Going metric at the same time
seems reasonable.
> The aviation industry is also very conservative, for instance with
> communication equipment. The radios are still AM, when everyone else
> have converted to FM or digital for a long time ago.
Yes.
Howard W. LUDWIG
I am accessing this thread via comp.std.internat, not
comp.text.tex, so, not being a LaTeX user (although I have
heard a lot about it, so perhaps I should become one :-),
I am unfamiliar with where you guys keep such documentation.
The reason I referenced the BIPM and NIST WWW sites is to
avoid bickering and flame wars over what SI and the metric
system are in various peoples' opinion, ancient recollection,
etc. BIPM is the official organization supporting CGPM,
which was assigned responsibility, in the Treaty of the
Meter, for defining and maintaining the metric system (now
SI). NIST is responsible for establishing the use, and the
rules for use, of the metric system in the USA, and has
people serving as part of the CGPM and various consultative
committees of CGPM; as part of this effort, NIST has been
the center of WWW-dissemination of correct information
regarding SI. You cannot get more official than those two
sites.
Howard W. LUDWIG, Ph.D.
Pete Forman
Thorsten> [ alert: this is waaaaay off-topic ... ]
Thorsten> Rebecca and Rowland write:
>> How many people *really* use Tera *and* atto on a regular basis?
Thorsten> I do :-).
Thorsten> Tera as in TeV (that's 10^{12} electron Volts) for
Thorsten> energies and atto as in attobarn (that's 10^{-18}\cdot
Thorsten> 10^{-10}cm^{-2}) for cross sections.
Hmmm, I thought we were talking SI. nJ (nanojoules) and ym2 (square
yoctometers) would be more appropriate.
--
Pete Forman
Western Geophysical
pete....@westgeo.com
Toby Speight
0> In <URL:news:36ABAFF1...@imbolc.ucc.ie>, Peter wrote:
Peter> A bit like the proposal that we should change from driving on
Peter> the left to driving on the right...gradually? :-)
Oh yes. Freight in the first year; buses & coaches change in the
following year; and other vehicles (inc. private cars) in the third
year. ;-)
Rebecca and Rowland
[snip]
> Hmmm, I thought we were talking SI. nJ (nanojoules) and ym2 (square
> yoctometers) would be more appropriate.
Yocto? Burn the witch!
Thomas Ruedas
>>Peter> the left to driving on the right...gradually? :-)
>Oh yes. Freight in the first year; buses & coaches change in the
>following year; and other vehicles (inc. private cars) in the third
>year. ;-)
You mean those whom the freight, buses & coaches didn't manage to kill
in the first two years...
--
--------------------------------------------
Thomas Ruedas
Institute of Meteorology and Geophysics,
J.W. Goethe University Frankfurt/Main
Feldbergstrasse 47 D-60323 Frankfurt/Main, Germany
Phone:+49-(0)69-798-24949 Fax:+49-(0)69-798-23280
e-mail: rue...@geophysik.uni-frankfurt.de
http://www.geophysik.uni-frankfurt.de/~ruedas/
--------------------------------------------
Peter Flynn
> Yes, I was somewhat surprised to find when I moved from Europe to the
> U.S. that engineers here don't use nF. I consider it to be another
> manifestation of the U.S. being reluctant to adopt new units (whereas
> they still use things like "microinches"...)
I was confused when comparing my blood cholesterol level with a US
colleague. I can't even remember the numeric values now, but mine
was in the hundreds (presumably mmol/l) and his was in the single
digits (presumably teaspoons per gallon or something :-)
What was that unit that Jerry Pournelle used for the speed of light?
Furlongs per fortnight?
Maurizio Loreti
> What was that unit that Jerry Pournelle used for the speed of light?
> Furlongs per fortnight?
From the 'jargon file':
:attoparsec: /n./ About an inch. `atto-' is the standard SI
prefix for multiplication by 10^(-18). A parsec
(parallax-second) is 3.26 light-years; an attoparsec is thus
3.26 * 10^(-18) light years, or about 3.1 cm (thus, 1
attoparsec/{microfortnight} equals about 1 inch/sec). This unit
is reported to be in use (though probably not very seriously) among
hackers in the U.K. See {micro-}.
:micro-: /pref./ ... 2. A quantifier prefix, calling for
multiplication by 10^(-6) (see {{quantifiers}}).
Neither of these uses is peculiar to hackers, but hackers tend to
fling them both around rather more freely than is countenanced in
standard English. It is recorded, for example, that one CS
professor used to characterize the standard length of his lectures
as a microcentury -- that is, about 52.6 minutes (see also
{attoparsec}, {nanoacre}, and especially
{microfortnight}). ...
:microfortnight: /n./ 1/1000000 of the fundamental unit of time
in the Furlong/Firkin/Fortnight system of measurement; 1.2096 sec.
(A furlong is 1/8th of a mile; a firkin is 1/4th of a barrel; the
mass unit of the system is taken to be a firkin of water). The VMS
operating system has a lot of tuning parameters that you can set
with the SYSGEN utility, and one of these is TIMEPROMPTWAIT, the
time the system will wait for an operator to set the correct date
and time at boot if it realizes that the current value is bogus.
This time is specified in microfortnights!
Multiple uses of the millifortnight (about 20 minutes) and
{nanofortnight} have also been reported.
--
Maurizio Loreti http://wwwcdf.pd.infn.it/~loreti/mlo.html
Un. of Padova, Dept. of Physics - Padova, Italy lor...@padova.infn.it
Paul Hardy
> What was that unit that Jerry Pournelle used for the speed of light?
> Furlongs per fortnight?
I remember some playing with conversion tables that I did many years ago
as a student, concerning the acceleration due to gravity (g).
Standard value is g = 9.81 m/s/s (metres per second per second),
This is commonly approximated to 10 m/s/s.
However, g corresponds even more accurately to:
1 light year per year per year,
or
1 Megametre per month per month
The first of these two implies that if relativity didn't intervene (but it
does), then a rocket accelerating at standard gravity would reach lightspeed in
a year!
--
Paul Hardy (PGH), Software Production Manager, Laser-Scan Ltd,
Science Park, Milton Rd, CAMBRIDGE, CB4 0FY, GB. Tel: +44 (0)1223 420414
Fax: 420044, Email: Pa...@LSL.co.uk, Web: http://www.Laser-Scan.com
Good judgement is the result of experience ...
... Experience is the result of bad judgement. (Fred Brooks)
George Jefferson
:
:This is commonly approximated to 10 m/s/s.
yes commonly introducing a 20% error. Actually, g is commonly
approximated to 10 (no units), its an odd sort of problem IMO
but its not such a good thing for people to have such confidnece
in the consistancy of the units that they neglect to carry
them through a calculation.
Paul Hardy
( George Jefferson ) writes:
> Paul Hardy wrote:
>> > :Standard value is g = 9.81 m/s/s (metres per second per second),
>> > :This is commonly approximated to 10 m/s/s.
>
2% surely ?
George Jefferson
:
:2% surely ?
DOH!
on that note, I'll resign from this discussion (for the time being..<g>)
Robin Fairbairns
>> > metric system would be so obviously disastrous.
>>
>> There would be some pain during the transition, but I think "obviously
>> disasterous" is a bit overstated.
>
nah, driving on the right is a nasty european thing, so willyum vague
would have us delay until it's proven to work.
then we'll apply to change, and de gaulle will say `non'.
--
Robin Fairbairns, Cambridge
Roy Smith
> yes commonly introducing a 20% error.
That's 20 d% (decipercent) :-)
Daniel Silevitch
George Jefferson <geo...@sol1.lrsm.upenn.edu> wrote:
>:Standard value is g = 9.81 m/s/s (metres per second per second),
>:
>:This is commonly approximated to 10 m/s/s.
>
I assume you mean 2%....
(and for a reasonably large number of calculations, a 2% error in the
strength of local gravity is Not That Bad)
-dms
Maurizio Loreti
> :> yes commonly introducing a 20% error. ...
> :
> :2% surely ?
>
> DOH!
Like taking 3 for \pi ... Are you from Indiana?
Bodo Moeller
> mg...@cl.cam.ac.uk (Markus Kuhn):
>> Metric Font Sizes
>> -----------------
>> DIN 16507-2 defines (among many others) the following two font
>> measures:
>> Font Size (German: Schriftgröße)
[...]
>> Font Height (German: Oberhöhe)
>> This is the height in mm of letters such as k or H. Typically,
>> the font height is around 72% of the font size, but this is of
>> course at the discretion of the font designer.
> If the majuscule height is approximately 72 % of the "Font Size", then
> presumably the "font size" is -- in accordance with the traditional
> terminology -- the body size ("Kegelhöhe"); e.g. about 4.23 mm for
> what is now called a "12 pt font", if we use Didot points. Actually,
> the percentage of the body size that is used for a typical capital
> letter ("Font Height") varies between European and US fonts: If I
> remember correctly, it's around 67 % or something like that for fonts
> based on Didot points, while your 72 % figure looks more like the
> U.S. version -- I think foundries chose these values so they could use
> the same type designs without scaling for the same point size at
> both European and US markets even though the total size of the metal
> type was larger in Europe (around 4.51 mm, i.e. 12 Didot points) than
> in the US (around 4.23 mm).
The version of a DIN 16507-2 draft I could now get hold of (I did not
check for the revision date) notes that the font size (Schriftgröße)
can be specified (depending on the typesetting system used) in one of
two ways: Either majuscule height (Versalhöhe) or body size
(Kegelhöhe), and the ratio of the latter to the former is typically
3:2, if Didot measures are used (2.3.2 Anm. 2: "Kegel und Versalhöhe
stehen in der Regel (System Didot) im Verhältnis 3:2 zueinander").
Later in the draft we can find the ratio for Pica measures: It's 70.9 %
(and a rounded figure 66.7 % for Didot is also given).
A Didot point is slightly more than 0.376 mm, so the majuscule height
for a "12 p" font is 3.01 mm (= 0.376 mm * 12 * .667). For a "Pica
point" of 0.3515 mm, a similar computation (0.3515 mm * 12 * .709)
results in 2.99 mm -- that's close enough, hopefully, to support my
conjecture that the different percentages come frome the desire to use
the same metal designs in both the Didot and Pica world. (Markus' 72 %
appear a little bit too much.)
> This "font size" is _not_ the recommended baseline distance.
A note to this effect can also be found in the Annotation to section
2.4.1 of the copy of the DIN 16507-2 draft I looked at.
Tor Arntsen
p...@sktb.demon.co.uk (Paul L. Allen) writes:
>In article <78g0ut$oso$1...@readme.online.no>
> t...@spacetec.no (Tor Arntsen) writes:
>> As somebody else said, maybe that's some US thing? Sounds really
>> strange to me though, as nanofarad is totally familiar to me. I've
>> seen enough US schematics but maybe I just haven't noticed that there
>> weren't any nF there..?
>
>on drawings and rubbed off components. Dirt marks on drawings can look
[...]
A little misunderstanding I think, as what I was commenting on in my reply
wasn't what it said about 2n7 as an alternative to using decimal points
(I'm very familiar with that), it was about the discussion about the absence
of nF (nanofarad) as a measure of capacitance. I and others wandered if the
non-use of nF could be some US thing..?
- Tor
Tor Arntsen
r...@cl.cam.ac.uk (Robin Fairbairns) writes:
>In article <36ABAFF1...@imbolc.ucc.ie>,
>Peter Flynn <pfl...@imbolc.ucc.ie> wrote:
>>Roy Smith wrote:
>>A bit like the proposal that we should change from driving on the left
>>to driving on the right...gradually? :-)
>
>nah, driving on the right is a nasty european thing, so willyum vague
>would have us delay until it's proven to work.
The swedes used to drive on the left, then one night they switched to
driving on the right[1]. I think it was around 1967 but I could be wrong
(I was a young kid then and I remember the event better than the time).
As far as I remember they stopped all traffic for some hours after
midnight, removed the covers from all the new signs and covered up
the old ones, and then started up the traffic again. It all went amazingly
smooth, except for the occasional Norwegian going on vacation, accustomed to
switch side at the border and forgetting all about the change :-)
- Tor
Footnotes:
[1] It should be mentioned though that the swedes had the steering wheel
on the left side also when they drove on the left side, so the change to
driving on the Right Side was maybe easier than it would be for you guys :-)
Markus Kuhn
Many European countries have introduced in the mid 1970s laws to
gradually phase-out the use of non-metric units in trade. These laws
allow a combined notation with the metric unit in the more prominent
place until 1999, December 31. After that date, labeling regulations
do not allow any more to make statements on product packaging and
documentation in inches, pounds, horsepowers, etc. These regulations
have later been taken up by the EU and are now in force in all EU
countries. Old units such as horsepower etc. have already vanished
practically completely from any EU produced product over the past few
years, so there is very little going to change for most EU manufacturers.
The 2000 ban of non-metric units might however require some serious
action by the US exporting industry. If you are a US typographer
designing product documentation that contains non-metric units, it
might be prudent for you to inform your customers about the European
Union metric-only labeling Directive (EEC 80/181) and it's
implications.
Assistance for US industry in dealing with metric conversion is
e.g., available from
http://lamar.colostate.edu/~hillger/
EEC 80/181 and amendments are available on
http://europa.eu.int/eur-lex/en/lif/dat/en_380L0181.html
There were last year some reports about very intensive US lobbying
efforts to convince the EU to delay implementation of the metric-only
directive by another 10 years, but I couldn't find any indication that
this has actually been implemented. At the moment is seems to me
that the 2000 deadline is fully in force and that we will soon
be able to buy 90 mm floppy disks instead of "3.5 inch" ones (which
by the way are really a Japanese fully metric (90.00 mm wide)
design).
Markus
--
Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
Louis Vosloo
> May be one useful reminder in this thread:
>
> The 2000 ban of non-metric units might however require some serious
> action by the US exporting industry. If you are a US typographer
> designing product documentation that contains non-metric units, it
> might be prudent for you to inform your customers about the European
> Union metric-only labeling Directive (EEC 80/181) and it's
> implications.
>
> Assistance for US industry in dealing with metric conversion is
> e.g., available from
>
> http://lamar.colostate.edu/~hillger/
How considerate of them.
It will be interesting to see if anyone in the typographical world cares.
Even in Europe.
Has URW, LinoType, MonoType, etc. changed their font size specification
to metric yet? I'd like to order a font designed for 3.5277777777... mm.
Or operating systems and applications? I can just see all MS and Apple
operating systems and all DTP applications switching to metric font size
specifications when the millenium roles over. Yeah right.
Tor Arntsen
>gradually phase-out the use of non-metric units in trade. These laws
>allow a combined notation with the metric unit in the more prominent
>place until 1999, December 31. After that date, labeling regulations
>do not allow any more to make statements on product packaging and
>documentation in inches, pounds, horsepowers, etc. These regulations
Just a couple of points:
- I remember when they started to use kilowatts as the main unit for
car motors, with horsepower as a second unit (in parentheses, as it were).
- That was a long time ago, and I haven't seen kilowatts for a long long
time! Horsepower it is.
From my experience with that (I was still young at the time and should have
been able to switch my mindset to kilowatts easily) I conclude that to
use the old and new unit in parallel is a BIG MISTAKE!. Nobody managed
to switch, and they gave up the whole thing.
Just go ahead and print '500 grams' or '1 kilo' on the flour and sugar
and onion bags, and leave it at that. Don't ever again mention what it
'amounts to' in the old unit. That way people are forced to associate
a certain (new) unit with some mental image of some amount of grocery,
instead of trying to remember what it amounts to in the old unit. The
latter leads to nowhere, the former is something humans are good at and
it *will work*. They just don't try it if the convertion option (which
is no good because there is no mental image associated with it) is available.
Just switch completely from day one, the 'gradual phase-out' only makes
the whole thing a long painful nothing.
- Tor
Jan Roland Eriksson
>Or operating systems and applications? I can just see all MS and Apple
>operating systems and all DTP applications switching to metric font size
>specifications when the millenium roles over. Yeah right.
Except for just font size specifications, MS-Word97 for Windows9x/NT is
in fact very close to be fully metric already.
It readily accepts cm, as well as all other more traditional units, for
every kind of sizing you want to do, except just font size. But I would
be surprised if it will not be there in the next version.
--
Jan Roland Eriksson <r...@css.nu> <URI:http://css.nu/>
George Jefferson
:gradually phase-out the use of non-metric units in trade. These laws
:allow a combined notation with the metric unit in the more prominent
:place until 1999, December 31.
seriously, american companies are required to produce seperate
packaging for export (most do anyway I'm sure, but still..)
Can you buy a dozen eggs in europe, or has the Committee passed
law requiring only units of 10?
George Jefferson
:Except for just font size specifications, MS-Word97 for Windows9x/NT is
:in fact very close to be fully metric already.
older versions are internally points, if you specify say a tab
location in cm it gets rounded to a point measure.
I would basically be amazed beyond belief if they changed that
without introducing thousands of new "features".
Christoph Nahr
>The 2000 ban of non-metric units might however require some serious
>action by the US exporting industry. If you are a US typographer
>designing product documentation that contains non-metric units, it
>might be prudent for you to inform your customers about the European
>Union metric-only labeling Directive (EEC 80/181) and it's
>implications.
Care to provide some quotes that actually talks about *typographic*
units? I read the EU document...
> http://europa.eu.int/eur-lex/en/lif/dat/en_380L0181.html
...and they don't mention it at all. Here's Article 2 which defines
the range of application of this document:
>Article 2
>
>(a) The obligations arising under Article 1 relate to measuring
>instruments used, measurements made and indications of quantity
>expressed in units of measurement, for economic, public health,
>public safety or administrative purposes.
>
>(b) This Directive shall not affect the use in the field of air and sea
>transport and rail traffic of units, other than those made compulsory
>by the Directive, which have been laid down in international conventions
>or agreements binding the Community or the Member States.
Note that 2a lists *economic* but not *technical* purposes. If you
were selling a product in *quantities* of pica points, as opposed to
meters, then you would have to change that measurement to meters.
However, since typographic units such as points do *not* denote any
economically relevant quantity but only a qualitative technical aspect
they are untouched by this regulation. At least that's my take on it.
>There were last year some reports about very intensive US lobbying
>efforts to convince the EU to delay implementation of the metric-only
>directive by another 10 years, but I couldn't find any indication that
>this has actually been implemented. At the moment is seems to me
>that the 2000 deadline is fully in force and that we will soon
>be able to buy 90 mm floppy disks instead of "3.5 inch" ones (which
>by the way are really a Japanese fully metric (90.00 mm wide)
>design).
I don't see anyone in Germany selling "90 mm" floppies. The only case
where advertisements were forced to use metric rather than imperial
units was with monitors because in this case, the size actually
corresponded to the economic value of the product and thus had to be
transparent to the consumer. Not so with purely technical details
such as typographic size or disk formats.
--
Chris Nahr (cnahr@ibmnet, insert dot after ibm to reply by e-mail)
Please don't e-mail me if you post! PGP key at wwwkeys.ch.pgp.net
Rebecca and Rowland
> In article <791l6k$832$1...@pegasus.csx.cam.ac.uk>,
> mg...@cl.cam.ac.uk (Markus Kuhn) writes:
> >May be one useful reminder in this thread:
> >
> >Many European countries have introduced in the mid 1970s laws to
> >gradually phase-out the use of non-metric units in trade. These laws
> >allow a combined notation with the metric unit in the more prominent
> >place until 1999, December 31. After that date, labeling regulations
> >do not allow any more to make statements on product packaging and
> >documentation in inches, pounds, horsepowers, etc. These regulations
> [...]
... don't apply to everything :-) Come January 1st 2000, I'll still be
buying beer and milk in pints in the UK.
> Just a couple of points:
> - I remember when they started to use kilowatts as the main unit for
> car motors, with horsepower as a second unit (in parentheses, as it were).
> - That was a long time ago, and I haven't seen kilowatts for a long long
> time! Horsepower it is.
The power of my motorcycles (as stamped on the frame) is expressed in
watts. These are Japanese motorcycles in the UK.
> From my experience with that (I was still young at the time and should have
> been able to switch my mindset to kilowatts easily) I conclude that to
> use the old and new unit in parallel is a BIG MISTAKE!. Nobody managed
> to switch, and they gave up the whole thing.
Hmm... I've been brought up using imperial and metric in parallel, and
I'm quite happy with kilograms or pounds, inches or millimetres, and so
on. I've never had any need to use kilometres `in real life', because
kilometres just aren't used in everyday life in the UK. So I use miles
exclusively when thinking about travelling places.
I suppose the big problem is that while yards and metres, pounds and
kilograms are easy to deal with in parallel (yards and metres are about
the same, so `about 200 yards' is the same as `about 200 metres'; while
`about 2 pounds' is `about 1 kilogram'), there's no straightforward way
of switching an estimate from HP to watts, especially since there's a
couple of definitions of HP still in use that I know of (`real' imperial
horse power, and that funny German version ;-)
[snip]
Rebecca and Rowland
[snip]
> I don't see anyone in Germany selling "90 mm" floppies.
No? I can see 90mm floppies in the UK, where inches are still very
common. I've just checked a box of 3.5 inch floppies I've got, made in
the USA, and the size is marked as 90mm as well as 3.5 inches.
> The only case
> where advertisements were forced to use metric rather than imperial
> units was with monitors
Whereas monitor sizes in the UK are still specified in terms of inches.
Rebecca and Rowland
> :Many European countries have introduced in the mid 1970s laws to
> :gradually phase-out the use of non-metric units in trade. These laws
> :allow a combined notation with the metric unit in the more prominent
> :place until 1999, December 31.
>
> seriously, american companies are required to produce seperate
> packaging for export (most do anyway I'm sure, but still..)
No they're not: they can use the same packaging inside the USA if they
wish. There's no laws against metric units inside the USA, and since
the USA officially adopted metric units before I started school AFAIK,
this ought to be the preferred form of labelling.
> Can you buy a dozen eggs in europe, or has the Committee passed
> law requiring only units of 10?
I think eggs in tens was an idea that the EC wanted to impose, but eggs
are sold in dozens and half dozens in the UK at least.
H. Peter Anvin
By author: real-addr...@flur.bltigibbet (Rebecca and Rowland)
In newsgroup: comp.std.internat
>
> > Can you buy a dozen eggs in europe, or has the Committee passed
> > law requiring only units of 10?
>
> I think eggs in tens was an idea that the EC wanted to impose, but eggs
> are sold in dozens and half dozens in the UK at least.
>
Same in Sweden, but that is somewhat of a funny case because in the
old days, eggs were commonly sold in units of 20 ("tjog")...
-hpa
--
"Linux is a very complete and sophisticated operating system. There
are, and will be, large numbers of applications available for it."
-- Paul Maritz, Group Vice President for Platforms And Applications,
Microsoft Corporation [Reference at: http://www.kernel.org/~hpa/ms.html]
Stephen Harker
> Christoph Nahr <cn...@seemysig.invalid> wrote:
>
> > I don't see anyone in Germany selling "90 mm" floppies.
>
> No? I can see 90mm floppies in the UK, where inches are still very
> common. I've just checked a box of 3.5 inch floppies I've got, made in
> the USA, and the size is marked as 90mm as well as 3.5 inches.
I remember finding some IBM disks labelled 9 mm (actually they said
8.9 mm) around 1985 in Australia. I must say they looked somewhat
bigger. I always intended to keep one for a talking point.
--
Stephen Harker s-ha...@adfa.edu.au
School of Physics Baloney Baffles brains: Eric Frank Russell
University College
UNSW, ADFA