




Date: Mon, 20 Feb 1995 16:17:06 -0400
From: Brian Ewins <gapv64@udcf.gla.ac.uk>
Subject: Re: Reading FTP files...

I have no trouble viewing or printing PS files, but then I have
a large collection of toys for viewing such things.

Somebody asked,so heres some info
On file formats and the why/why not:

GIF : actually GIF87 or GIF89. these are excellent lossless image formats
        especially for b&w pictures as they compress long runs of single
        colours very well. Poorer for e.g. photos of models, 24-bit colour.

        BUT: aside from the "can't scale it" issue, UNISYS, who hold the
        patent on LZW compression (which GIF uses) have started applying it, and
        are suing CompuServ, where the format first appeared. So now,
        it's not PC to use GIFs any more. There is a fighting fund to help
        in this court case... I don't have the address on me but the
        announcement about this was widely posted recently.

JPEG : not very good for b&w images, excellent for 'real' images (like large
        colourful photos.)
        It's not really a good idea to make origami diagrams as JPEGs.

PostScript: a cool page description language (not a 'graphics format' as such).
        If you have line drawings, (like origami diagrams), then PS files tend
        to be small. (eg. look at how small the output of Maartens' oridraw
        program can be). It's also plain ASCII (at least level1 PS, which is
        what all of the files on the archive are), so you can download it
        faster using ftp. It also looks nice at any size (sometimes!)
        There are 3 big problems with PS :
        1. PS printers cost a helluva lot more
               However, using GhostScript (for example) or some other PS inter
               -preter gets you to any other format you like.
        2.Most programs that say 'I understand PS' really mean EPS (a single
        page format...most of the diagrams on the archive are actually legal
        EPS)
        3.Some programs that do understand real PS demand to see comments in it
        to find out where pages end. This causes some problems with the output
        of Oridraw.

Other vector formats (eg wmf, rtf) arent very portable, and other bitmap formats
are either rubbish (eg BMP) or great but not very widely used (eg TIFF)

So... either use GIF and feel guilty or use PS.

        I think the reason that the archive is mainly PS is just inertia,
if people submit diagrams in GIF format then things will change.

               Baz.





Date: Mon, 20 Feb 1995 16:26:33 -0400
From: Doug Philips <dwp+@transarc.com>
Subject: Postscript popularity (was: Reading FTP files...)

In message <199502201905.AA16787@dorsai.dorsai.org> Sheldon Ackerman wrote:
+I don't know how many individuals subscribe to this list but I'd be curious
+to know how many have actually gone to the archive and been able to view
+some of the postscript files. Personally, my Canon InkJet is not a
+postscript printer. I did find a program called Ghostscript which allows me
+to view and print these files, but it is no easy task. Any format that one
+usually finds clipart is certainly easier for me.
+
+So how many of you out there can actually view those files and have actually
+done so?

I have printed off all the model diagrams and articles/papers with no
problems.  This is a generally hard problem of how to disseminate "print
quality" information in electronic form.  The up-side to PostScript (as
others have/ will point out), is that it is is straight ascii, no hassles
with "binary" transfers and GIF conversions from MAC to PC to Unix formats,
etc., etc., etc.  The down side is that you need a postscript interpreter.

To me, having the stuff on line is great for having access to it, but I never
want to view it online.  I don't want to have to have a computer handy to fold
from diagrams, or read origami articles, I want high quality output that I can
stuff in my backpack, or notebook, or file away with my origami books, or use
in any number of "offline" ways.

Frankly, I don't think it really matters what format it is in, there will
_always_ be someone who is a newbie at reading or printing PostScript/GIF/
JPEG/PICT/Foo/Bar files and will need help.  That is just something that has
to be acknolwedged and handled.  For the majority of platforms, there are
viewers for all those formats, so print quality (again, this is my personal
concern) is the issue.

Well, that was my $0.02 anyways!

-Doug





Date: Mon, 20 Feb 1995 17:26:31 -0400
From: JanetJWH@aol.com
Subject: Re: Shareware: DIRECTLY E-MAI...

Someone mentioned on the list recently that they had written a rather
detailed paper on the history of Origami.  I would like to get a copy a the
paper.  Could whoever mentioned it post the info again.  If it is available
electronically, please email to me at JanetJWH@aol.com, or post a snail-mail
address and I will be glad to send a SASE.

Thanks in advance,
Janet





Date: Mon, 20 Feb 1995 17:35:07 -0400
From: chee.tang@eng.ox.ac.uk (Chee Tang)
Subject: Re: Postscript popularity (was: Reading FTP files...)

> To me, having the stuff on line is great for having access to it, but I never
> want to view it online.  I don't want to have to have a computer handy to fold
> from diagrams, or read origami articles, I want high quality output that I can
> stuff in my backpack, or notebook, or file away with my origami books, or use
> in any number of "offline" ways.
>
> Frankly, I don't think it really matters what format it is in, there will
> _always_ be someone who is a newbie at reading or printing PostScript/GIF/
> JPEG/PICT/Foo/Bar files and will need help.  That is just something that has
> to be acknolwedged and handled.  For the majority of platforms, there are
> viewers for all those formats, so print quality (again, this is my personal
> concern) is the issue.
>
> Well, that was my $0.02 anyways!
>
> -Doug
>

I quite agree with Doug. But as someone both new to the list and with virtually
     no previous experience of Postscript format files, I would like to know
     how to download and print off these .ps files.

Is it simply a matter of downloading and writing to the printer port (on a PC)?
Sorry if this has been said before, and is obvious, but I don't recall any
     explicit instructions.

I think it is superb that designs can be transmitted to the world in this way.
     Unfortunately some of us are having difficulty with the reception.

Chee Fai.

Chee Fai Tang
Dept. of Engineering Science
Oxford University
U.K.





Date: Mon, 20 Feb 1995 20:48:56 -0400
From: AFAAndy@aol.com
Subject: Re: Reading FTP files...

>>>I don't know how many individuals subscribe to this list but I'd be
curious
to know how many have actually gone to the archive and been able to view
some of the postscript files. Personally, my Canon InkJet is not a
postscript printer.<<<

I have downloaded all the files in the archive. There is only one I haven't
been able to use. I can't remember which one it is. What I have done is to
convert them to Adobe Acrobat Files using Distiller from Adobe Acrobat Pro.
These files will work on PC and Mac. All you need is the free viewer.

This doesn't work for UNIX users though.

If someone would like all the files uploaded to a FTP site let me where and
I'll upload them and the Viewers.

Andy





Date: Mon, 20 Feb 1995 20:52:34 -0400
From: AFAAndy@aol.com
Subject: Re: Reading FTP files...P.S.

Oh, that's if none of the authors object :)

Some look ok on screen but they all print out pretty nice at 300 dpi.

Andy





Date: Tue, 21 Feb 1995 01:32:29 -0400
From: Valerie Vann <75070.304@compuserve.com>
Subject: Postscript on PC

Some comments on PS files:

They are ASCII & emailable, BUT if they contain photos or info that
must be bitmapped, while still ASCII, they can be very large. I found
from reading messages in various compuserve forums that many folks
are getting email on systems with a file size restriction, so large PS
files must be attached as files. Large ones take time to download too.

Still, at work where I have access to a PS printer, it is my choice
for format as greyscale, color, typesetting etc are much less hassle
in PS and it is universally well supported in all high end word
processing and publishing programs.

Output: On a PC all you have to do with a PS printer is use the DOS
copy command eg.   copy foobar.psc PRN
This just "dumps" the file to the printer, and since PS is a "language"
that PS printers "interpret", the PC doesn't have to know anything
about it. There are as some folks pointed out here, and occasional
problem with non-resident fonts or files "headers" or multipage files,
but not often.

Also on a PC: The industrial strength wordprocessing programs like
Wordperfect will import most PS files into a graphics box (which can
be page size). You will not be able to SEE what it looks like, but
when you print the document on a PS printer, the graphic comes out.

300 dpi & popularity of PostScript: Most non-entry level MAC setups
where wordprocessing and/or graphics are done have a PS printer. They
were much more common on MACs before PCs. And 300 dpi was the standard
"high resolution" printing density for office level PS (and HP laser
jets too) until recently. Now 600 is becoming pretty standard. In PC
business locations the high end printer is usually an HP LaserJet, but
LaserJets with a PostScript option ($250 plus maybe some more memory)
is becoming increasingly more common too.

I too prefer a printable file for paper output; even a hi-res 17 inch
monitor lacks the resolution for anything but simple diagrams, and you
can't write on the monitor...

--valerie     Valerie Vann        compuserve: 75070,304
INTERNET:     vvann@delphi.com                          ____
      or:     75070.304@compuserve.com                 /___/|
>> It is the art of engineering to reach         <<   |\./| |
>> sufficient conclusions from insufficient data <<   |/ \| /





Date: Tue, 21 Feb 1995 02:35:08 -0400
From: Joseph Wu <jwu@cs.ubc.ca>
Subject: Re: Reading FTP files...

On Mon, 20 Feb 1995 AFAAndy@aol.com wrote:

> I have downloaded all the files in the archive. There is only one I haven't
> been able to use. I can't remember which one it is. What I have done is to
> convert them to Adobe Acrobat Files using Distiller from Adobe Acrobat Pro.
> These files will work on PC and Mac. All you need is the free viewer.
>
> This doesn't work for UNIX users though.

Not so. As Alex Barber could tell you (he told me), there are UNIX
versions. And the benefit of PDF files is that they are  generally much
smaller than PS files.

> If someone would like all the files uploaded to a FTP site let me where and
> I'll upload them and the Viewers.

This is fine with me.

Joseph Wu      <jwu@cs.ubc.ca> | Witty quote is now back to the
Master's Student               |   drawing board due to squeamish
University of British Columbia |   readers. Any suggestions?
WWW: http://www.cs.ubc.ca/spider/jwu/origami.html (Origami Page)





Date: Tue, 21 Feb 1995 06:39:33 -0400
From: "Mr B.R. Stephens" <bruce@liverpool.ac.uk>
Subject: Re: Reading FTP files...

> So how many of you out there can actually view those files and have actually
> done so?

I had no problem.  I use ghostscript, which I believe is available for
PCs and Macs as well as the UNIX workstation I use.  I'm also sure this
has come up repeatedly before, and I thought ghostscript was in the
FAQ, also available from the ftp site.

--
Bruce                   Institute of Advanced Scientific Computation
bruce@liverpool.ac.uk   University of Liverpool





Date: Tue, 21 Feb 1995 09:20:30 -0400
From: Sheldon Ackerman <ackerman@dorsai.dorsai.org>
Subject: Re: Reading FTP files...

>  I use ghostscript, which I believe is available for
> PCs and Macs as well as the UNIX workstation I use.
I think I originally called it ghostscript but upon reading one of Joseph
W's posts where he called it Ghostview I stand corrected :-)
There may be another program called Ghostscript.

--
Sheldon Ackerman
ackerman@dorsai.dorsai.org
sheldon.ackerman@nycps.nycenet.edu





Date: Tue, 21 Feb 1995 12:02:03 -0400
From: bryan@sgl.ists.ca (Bryan Feir)
Subject: Re: Reading FTP files...

> I think I originally called it ghostscript but upon reading one of Joseph
> W's posts where he called it Ghostview I stand corrected :-)
> There may be another program called Ghostscript.

   Continuing with the NORM...

   Ghostscript is the 'core' program that actually performs the interpretation
of the Postscript program into an image; Ghostview is a second program that
runs 'on top of' ghostscript and displays that image, gives a nice user
interface to it, and allows you to pick out pages.  Ghostview will not run
unless ghostscript is there as well.  Also, there is a Windows version of it
called GSView; all are located at ftp.cs.wisc.edu under /pub/ghost.

   Next time, ORM, I promise...

---------------------------+---------------------------------------------------
Bryan Feir           VE7GBF|"You also ask, 'How fares my love across the sea?'
bryan@sgl.ists.ca          | Intermediate, I presume.  She would hardly travel
                           | steerage."               -- Stephen Leacock





Date: Tue, 21 Feb 1995 14:56:22 -0400
From: REEDS@zodiac.rutgers.edu
Subject: simple folds

I too delight in simple folds, and this electronic mailbox is good place, I've
     found, to share them. A case in point is the lovely 6-card cube that
Jeannette explained a few months ago. The model I'm proudest of inventing
is the chair, that uses the bar code on the otherwise obnoxious and ubiquitous
blow-in cards in magazines to make the chair back. (It's in one of the
Friends of the Origami Center Convention volumes--can't tell you which one
off hand). Just yesterday,on a bumpy airplane ride, I kept my neighbors
and me from worrying about the flight by folding every card we could find
into chairs (and the tables, cupboards that they can be slid together to
form).
Karen Reeds
Rutgers University Press
109 Church Street
New Brunswick NJ 08901
reeds@zodiac.rutgers.edu





Date: Tue, 21 Feb 1995 15:15:23 -0400
From: barber@starbase.neosoft.com (Alex Barber)
Subject: PDF files [was Reading FTP files]

I have added PDF versions of all the Postscript files on the FTP site to my
web page.  The address is http://starbase.neosoft.com/~barber - let me know
if this address doesn't work for you.

If anyone doesn't want me to mirror their diagrams/models as Acrobat PDFs,
please let me know.  I'm just trying to give people another way to view the
diagrams on Maarten's FTP site.

I have included pointers on my page to Adobe's web page and free Acrobat
viewers.  There are viewers for Acrobat 2 for Mac and Windows, and viewers
for Acrobat 1 for DOS and Sun OS/Solaris.

Regarding Ghostscript, there are viewers for Mac, Windows and X-Windows
that you can get from FTP sites - Wuarchive, Umich and Sumex-Aim are good
places to start, along with their mirror sites.  If there is enough space
on the FTP site, perhaps Maarten could add Ghostscript to one of the
directories, such as programs.

Alex Barber

barber@starbase.neosoft.com | http://www.printnet.com/abarber/barber.html

I will not be pushed, filed, stamped, indexed, briefed, debriefed or
numbered.  My life is my own.





Date: Tue, 21 Feb 1995 15:23:29 -0400
From: Kim Best <Kim.Best@m.cc.utah.edu>
Subject: Re: Reading FTP files...

On Mon, 20 Feb 1995, Brian Ewins wrote:

>
>       BUT: aside from the "can't scale it" issue, UNISYS, who hold the
>       patent on LZW compression (which GIF uses) have started applying it, and
>       are suing CompuServ, where the format first appeared. So now,
>       it's not PC to use GIFs any more. There is a fighting fund to help
>       in this court case... I don't have the address on me but the
>       announcement about this was widely posted recently.
>
>
> So... either use GIF and feel guilty or use PS.
>

Actually there is no reason to feel guilty about using GIF.  Unisys is
only asking for royalties for commercial software written from 1995 on
that uses the GIF format.  So if your gif converter is written before 1995
or it is public domain software, or even if it is commercial software and
the makers have payed the royalties to Unisys, you can use GIF with a
clear conciounce.  Unisys has made it quite clear they are not asking for
royalties on actual GIF files only the programs that create them or view
them.

Kim Best                                  *************************
                                          *      Origamists       *
Rocky Mountain Cancer Data System         *  Are good with their  *
420 Chipeta Way #120                      *        Hands          *
Salt Lake City, Utah  84108               *************************





Date: Tue, 21 Feb 1995 15:32:04 -0400
From: Kevin Nara Park <prank@leland.Stanford.EDU>
Subject: Re: Reading FTP files...

Hello, all,

        If you simply need to send a PostScript file to a PS printer on
the Macintosh, as I believe the person who initially asked this question
wanted, System 7.x comes with a program called LaserWriter Utility which
does just that.  On System 7.5 you may have to install it using Custom
Install, but once it is on your computer it gives you the option to
"Download a PostScript File."

        Also, opening the file using Simple Text (you may have to change
to file type to TEXT) or MS Word using PostScript as your text format
(you may have to change the document type filter in the Open File window

        Since Simple Text and LaserWriter Utility are free from Apple, I
generally prefer these by sheer price/performance ratio.  Uh huh.  Hope
that helps.

Kevin





Date: Tue, 21 Feb 1995 15:49:50 -0400
From: Laurie_Reynolds@smec.sel.sony.com (Laurie Reynolds)
Subject: Jerry Harris is my hero!

Greetings:

Jerry Harris's instructions for crimping and doing sinks were wonderful!
I have reposted them separately for those that missed it the first time.
I was having trouble with Lang's Chambered Nautilus and the Atlantic Sea
Urchin in the same book.  With the help of Jerry Harris's fantastic
instructions, I have been able to sort of do them.  I say sort of because,
as jerry predicted, I got stuck on the Sea Urchin.  My boss is back, and he
said that he would show me how to do steps 27-34.

I am no longer a sink/crimp-challenged origamiist :-)

Thanks Jerry!

laurie reynolds





Date: Tue, 21 Feb 1995 16:21:45 -0400
From: Laurie_Reynolds@smec.sel.sony.com (Laurie Reynolds)
Subject: Sink Tutorial

>Hello,
>
>I just bought the book "origami sea life" and after temporarily giving up
>on the chambered nautilus, I thought that I would try the atlantic purple sea
>urchin.  It seemed to have mostly the types of folds found on the frog, and
>lily, items that I can easily do.  BUT, he snuck in a sink fold, and I spent
>an hour ripping several models while I tried in vain to do a sink from step 20.
>
>Any hints on how to do a sink?
>
>
>thanks,
>laurie

Laurie (again! ) -

        Hey, two help messages in one day!  Gee, if _this_ keeps up we're
going to be fast friends!  ;-)

        Okay...sinks are another of those difficult folds that people
always run into trouble with!  >>>SIGH<<<....  There are two kinds of sink:
open, and closed.  Open sinks are easier -- they usually involve opening
up a portion of the paper to do the fold (hence the name).  Unfortunately,
Lang and Montroll's boook doesn't do the description of how to do these
folds justice, and Engel's book has the instructions for open and closed
sinks reversed!  (A bad typo...).  Whenever I teach sinks, I always use a
waterbomb base -- the broad, closed upper point of this base is good for
sinking.

        If you were to take the waterbomb base and fold some arbitrary
amount of the broad point down and unfold it, you'd have a nice, straight,
horizontal line.  But slowly unfold the base, while keeping an eye on that
line -- when the paper is flat, you'd see that the line you folded is
actually one side of a square!  Now, if you were to take each line that
makes a side of that square, and make them all into mountain folds, and
then refold the waterbomb base keeping the little square's mountain folded
sides in place, you'd end up with a waterbomb base whose broad, upper point
has been open sinked (sunk?).  (This, BTW, is the result of the diagram in
Lang and Montroll's book where they describe open sinks.)  Sinks, by
definition, occur in places where the lines do _not_ intersect an open
edge, except occasionally at just a point -- that is, the lines involved in
the sink do not hav contact with an open edge -- if they do, then they
become reverse folds, not sinks.  For anyone who's tried to fold many
British models, you've probably noticed a completely arbitrary interchange
of the words "sink" and "reverse fold."  No standardization...

        Anyway, back to sinks...the kind of sink _you_ want in Step 20 of
the "Urchin," is a closed sink (the harder kind -- of course!  8-)  )
Closed sinks to not involve opening up the paper; instead, you just have to
force the paper to pop directly from one place to another.  Rarely are
these neat folds; but that's OK because the crumpling of the layers usually
gets hidden away somewhere by the sinking process.   Closed sinks almost
always end up trapping some layers of paper -- that's why they're good for
locking mechanisms in folding.

        Imagine again, if you will , the waterbomb base.  Again, you've
creased some arbitrary amount of the upper point down.   Now, look inside
the waterbomb base (don't unfold it!) -- you'll see two large areas of
paper that lead up to the inside of the broad, upper point.  These are the
layers that are going to get trapped.

        Let's start off easy:  for this closed sink, we're only going to
hold _one_ of these inner layers together.  That is, let's just hold the
left side of the waterbomb base shut with one hand.  Now, open up the model
as far as you can -- you'll end up with a pyramidal model that's open on
the bottom (OK, OK, it's an irregular tetrahedron, but let's not be picky!
8-)  )  Notice that instead of the line you folded ending up as one side of
a square, as it did with the open sink, but now it's one side of a
triangle.  The triangle, of course, doesn't lie flat, like the square did.
Now, while still holding the left side shut, just force the portion of the
pyramid delineated by the triangle's lines down and into the body of the
waterbomb base.  Then you can close the model back up.  What you'll have is
a waterbomb base that still has the four points at the sides, but the two
points at the left side, where you held the layers together, are trapped
together at the top!  What you've actually done here is close sink edthe
left side of the model, but open sinked the right side.  To close sink the
whole thing, you'd have to hold _both_ sides together and push the top
point in!  _That's_ hard!  8-)

        Fortunately, Step 20 of the "Urchin" isn't so bad.  If you look at
the diagram, you'll see that the flap sticking off to the left?  Follow
it's bottom edge -- it changes direction right where the edge meets the
central, vertical axis of the model.  It's at that point where you'll push
to perform the closed sink.  (Don't worry about holding any layers together
here, though -- they're already trapped for you!  8-)  )  It's just a
matter of forcing the point inside-out, so that it points up, instead of
down.  The tip of the point is usually the hardest; you may have to get a
dull pencil or somesuch item to reach inside and force the tip out.

        But just wait!  8-)  The hard parts of this model are the incessant
repetitions of Steps 27-34 all through the model!  In essesence, doing
these steps is not unlike undoing a closed sink...but you'll see what I
mean!

        Again, I hope this helps!

Jerry D. Harris
Denver Museum of Natural History
2001 Colorado Blvd.
Denver, CO  80205
(303) 370-6403

Internet:  jdharris@teal.csn.net
CompuServe:  73132,3372
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
        "I repainted the picture Brown had painted for us.  A dying,
shrinking lake...these great...behemoths...dying..."
        "Well," she said, "all you tell me may be so...but I still can't
see why such creatures would have wanted to do it in the first place."
        "Do what, ma'am?"
        "Why, crawl away back under all that rock to die."

-- Roland T. Bird, _Bones for Barnum Brown_
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

----- End Included Message -----





Date: Tue, 21 Feb 1995 16:19:39 -0400
From: Laurie_Reynolds@smec.sel.sony.com (Laurie Reynolds)
Subject: Crimping tutorial

>Hello,
>
>I was trying to do the Chambered Nautilus model in Lang & Montroll's
>"Origami Sea Life" -  I got stuck on step 19 - crimp both bottom edges.
>
>Any suggestions?
>
>thanks,
>laurie

Laurie -

        The process of "crimping" in origami is a tricky thing, and, IMHO,
most diagrammers (even excellent ones like Lang and Montroll) screw up the
semantics when describing the procedure.  I hope I can help!

        Let's start at the beginning, with the simple procedure of
pleating.  I think everyone, even non-origami enthusiasts, understand
pleating!  Just about everyone, at some time or another, has pleated a
piece of paper, back and forth, like an accordion, to make a simple fan.
What are the characteristics of a pleat?  Well, after you fold a square up,
back and forth, like a fan or an accordion, unfold the paper and look at
the crease lines.  What do you see?  An alternating series of valley
mountain folds.  Notice _especially_ that none of the lines intersect;
they're all parallel to one another (and would remain so if extended onto
infinity).  That is, by definition, a pleat.  Steps 4-7 and 10-15 of
Montroll's "Cichlid" in the same book are all examples of pleating.  Step
17 of Lang's "Nautilus" is NOT pleating!!!  (Everyone get out their red
pens and correct this).

                                ____________________
                                |                                      |
                                |-----------------------------|
                                |                                      |
                                |-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-|
                                |                                      |
                                |-----------------------------|
                                |                                      |
                                |-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-|
                                |___________________|

        HERE'S A ROUGH TEXT-LINE DIAGRAM OF A SQUARE, PLEATED
        ---- IS A VALLEY FOLD,  -.-.-.- IS A MOUNTAIN FOLD.

        A crimp is a variation on this theme.  Crimping it similar to
pleating, except that the lines _do_ intersect!  A simple pleat would be
where the lines intersect right at the edge of the paper.  This is easy to
imagine:  take the piece of paper with all the pleats on it from the last
example -- the one with all the parallel pleat lines.  Now just put in a
series of folds that connects the left side of one pleat line that extends
to the right side of the pleat line below it.

                                ____________________
                                |                                      |
                                |-----------------------------|
                                | `---                                |
                                |       `---                          |
                                |             `---                    |
                                |                  `---               |
                                |                       `---          |
                                |                            `---     |
                                |________________`--- |

        HER'S A ROUGHT DIAGRAM OF A PLAIN CRIMP:  NOTICE THAT THE TWO LINES
INTERSECT IN THE UPPER LEFT.

        This is just plain, ordinary crimping.  A sample of this kind of
crimp is steps 20-21 of Lang's "Cuttlefish" in the same book.  Step 17 of
the "Nautilus," as you have by now deduced, is a crimp, NOT a pleat.

        Now, to compound the difficulty, there are two additional kinds of
crimps:  an inside crimp, and an outside crimp.  These terms have fallen
out of favor recently, but they are good terms because they differ from the
kind of crimp outlined above.  (In actuality,  the line is really blurry
between inside and outside crimps, but we won't delve into that right
now...  8-)  ).  The crimp you're having problems with in Lang's "Nautilus"
is an inside crimp.  These crimps share with the plain crimp the fact that
the lines intersect at some point; in the case of step 19, it's the top
edge.

        You can imagine performing Step 19 as two sets of plain crimps:
one on the top layer of paper, and one on the bottom.  That is to say:
look at the diagram.  Notice that the MOUNTAIN fold is always CLOSER TO THE
LARGE END OF THE MODEL than the valley fold line.  If you were to take that
diagram at face value, and just perform the folds as labeled, you'd end up
with Steps 17-18 all over again!  The mountain fold translates all the way
through the model to the other side; doing it this way -- with plain
crimps, like in Step 17 -- if you flipped the model over, you'd see a
series of fold lines where the VALLEY fold is always CLOSER TO THE LARGE
END OF THE MODEL!  This isn't what you want.  You want it so that, no
matter which side of the model you're looking at, the MOUNTAIN folds are
always CLOSER TO THE LARGE END OF THE MODEL.

        The best way to perform inside crimps like this, I've found, is to
hold one side of the model stewady in one hand, and use the other hand to
sort-of swivel the paper.  In the case of Step 19, you'd be best off
holding the LARGE end of the model and using your other hand to "swivel"
the SMALL end of the model inside.  Remember that the vertical line you see
in Step 19's diagram is also a mountain fold on the other side of the
model, and the diagonal valley fold line is likewise a valley fold on the
other side.  What is going to happen is that a small part of the SMALL end
of the model is going to get tucked inside, covered by a portion of the
LARGE end of the model.  The entire SMALL end of the model will be tilted
down somewhat -- in fact, the model will look similar to the diagram in
Step 16, except in _that_ diagram, the SMALL end lies on top of the LARGE
end.  If you've done it correctly, then the LARGE end will overlie the
SMALL end, no matter which side of the model you look at.

        Of course, the hardest part of this particular model is Step 22!  8-)

        I really hope this has helped a little -- it's inordinately
difficult to explain origami models with text alone!  If I can help some
more, please let me know.

Jerry D. Harris
Denver Museum of Natural History
2001 Colorado Blvd.
Denver, CO  80205
(303) 370-6403

Internet:  jdharris@teal.csn.net
CompuServe:  73132,3372
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
        "I repainted the picture Brown had painted for us.  A dying,
shrinking lake...these great...behemoths...dying..."
        "Well," she said, "all you tell me may be so...but I still can't
see why such creatures would have wanted to do it in the first place."
        "Do what, ma'am?"
        "Why, crawl away back under all that rock to die."

-- Roland T. Bird, _Bones for Barnum Brown_
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

----- End Included Message -----





Date: Tue, 21 Feb 1995 17:15:49 -0400
From: "Penelope R. Chua" <chupenr@minerva.cis.yale.edu>
Subject: Re: Reading FTP files...

On Tue, 21 Feb 1995, Kevin Nara Park wrote:

>       If you simply need to send a PostScript file to a PS printer on
> the Macintosh, as I believe the person who initially asked this question
> wanted, System 7.x comes with a program called LaserWriter Utility which
> does just that.  On System 7.5 you may have to install it using Custom
> Install, but once it is on your computer it gives you the option to
> "Download a PostScript File."

My recollection is that LaserWriter Utility only works on Apple
postscript printers - I tried it once on our Hewlett-Packard laserjet 4M
(from a Macintosh) and it didn't work... I myself have been using this handy
little shareware utility called DropPS that allows you to print out
postscript files merely by dragging and dropping the file onto the
application.  DropPS is available from most Mac archives.

--
Penelope Chua                 chupenr@minerva.cis.yale.edu
Department of Biology         (203) 432-5052
Yale University
219 Prospect Street
Box 6666
New Haven, CT 06511





Date: Tue, 21 Feb 1995 19:34:15 -0400
From: JanetJWH@aol.com
Subject: Re: Reading FTP files...

>>>I don't know how many individuals subscribe to this list but I'd be
curious
to know how many have actually gone to the archive and been able to view
some of the postscript files. Personally, my Canon InkJet is not a
postscript printer.<<<

I have been able to download and print all the files from the archive.  I use
a QMS 810 Postscript printer.  I have also used ghostscript to view them
online and print them to regular laserjet printers.

Janet





Date: Tue, 21 Feb 1995 21:24:10 -0400
From: KRPatel@ix.netcom.com (Kumar Patel)
Subject: Re: Reading FTP files...

>I'd be curious to know how many have actually gone to the archive and
been able to view some of the postscript files. Personally, my Canon
InkJet is not a postscript printer.

        I don't have a postscript printer either (HP LaserJet III) and I
doubt the majority of people who subscribe do.  I would use ghostscript,
but it doesn't support my printer.  It's also a very large program (4
megs) and I really don't have that much free space.  For me at least,
GIF would definetly be easier.
        As for print quality, I fail to see why this matters because
they are "just line drawings".  Also, GIF is pretty much the Internet
standard and most of the people out their have GIF viewers.  And,
archiving our models in a universal format will attract many more
uninitiated to this great art.

Bye for now,
Apurva Patel





Date: Tue, 21 Feb 1995 22:57:54 -0400
From: kbruce@vistanet.com (Kathleen Bruce)
Subject: Hello

Test message from James Bruce.

Hi. I am new to this list.  I am wondering how many people subscribe to this
list, and what levels are discussed?

I am experienced, and found this mailing list on Joseph Wu's WWW info pages...

James Bruce

c/o KBruce@vistanet.com





Date: Wed, 22 Feb 1995 00:18:22 -0400
From: MJNAUGHTON@amherst.edu
Subject: 30 Pointed Omegas

Valerie Vann wrote, responding to my explanation of the 30-unit Omega Star:

>Your explanation of the waterbomb base Omega star unit was fine. . . .
>
>You mention half blintzing to get short arms. When I build a 12 unit basic 12
>point star, it isn't necessary to have short arms.
>In fact it just makes unnecessary thickness on the folded down edges. And the
>the geometry is identical to the 6 unit one, you're still starting from the XYZ
>(3 intersecting planes) model. . . .

        You're absolutely right -- the half-blintzing isn't necessary, but I've
found that it does make the models easier to put together.  Not so much with
the 12-unit one (in fact, it make the XYZ phase _much_ more stable), but more
with the 30-unit one.  It also has the advantage of making it a little easier
to distinguish the flaps from the pockets (sometimes helpful for beginners! :-)

>However, even with short arms such as you describe for pockets, I don't see how
>you can get a 30-unit icosidodec. from the waterbomb unit you describe, since
>you'd need to put five together around the pentagon "faces" , and the central
>angle of the concave areas is too great as far as I can see . . . . What am I
>missing?

        It sounds as if when you make the 12-unit star you begin by making the
XYZ and then make the points to form the star, and you are trying to do the
same kind of thing with the 30-pointer.  You're right again -- it can't be
done! ;-)  The trick is to form the points as you go along. . . .  If you
imagine the 12-pointer as based on the cuboctahedron (with each vertex on the
polygon representing one point of the star), you can see that the "sink edges"
of the XYZ are folded _towards_ the triangular faces and _away_ from the
square faces.  (Sometimes I say that the triangles are "innies" and the squares
are "outies" :-).  The same principle is used with the 30-pointer (based on
the icosidodecahedron -- the triangles are still "innies", but now it's pen-
tagons that are "outies".  Usually I start by forming five modules into a
ring (folding points as I go), then using another five to complete the triangles
off each side (folding points all the way), then ten, then five, and finally
five.  By the way, those last couple of modules are a real bear to get in --
and worse if you don't blintz the water-bomb base!

        One further note -- because it follows this simple rule -- all triangles
are "innies", and all pentagons "outies" -- I think the 30-pointer is easier to
construct than the 24-pointer (based on the rhombicuboctahedron).  Here all
triangles are still "innies", but half the squares are also (those whose faces
all form sides of other squares), while the other half are "outies".  Speaking
from experience, it can be kind of confusing trying to remember which is which!

        I'm going to have to try your 30-piece, 60-pointer -- it sounds neat!
And thanks for the info on David Petty's model -- I'm going to look it up when
I'm at the convention next June.  Hope all this makes sense -- let me know if
you have more questions!

        Mike Naughton





Date: Wed, 22 Feb 1995 08:13:43 -0400
From: "M.J.van.Gelder" <M.J.van.Gelder@rc.rug.nl>
Subject: Re: PDF files [was Reading FTP files]

.. Alex Barber wrote:
m>Regarding Ghostscript, there are viewers for Mac, Windows and X-Windows
m>that you can get from FTP sites - Wuarchive, Umich and Sumex-Aim are good
m>places to start, along with their mirror sites.  If there is enough space
m>on the FTP site, perhaps Maarten could add Ghostscript to one of the
m>directories, such as programs.

You should have a look in the archives. There is a directory gsdos with the
MSDOS version of GhostScript. May be it is an old version, but it is there.

Maarten van Gelder, Rekencentrum RuG, RijksUniversiteit Groningen, Holland





Date: Wed, 22 Feb 1995 12:01:41 -0400
From: Alan Light <alight@panix.com>
Subject: Re: Reading FTP files...

> >
> > So... either use GIF and feel guilty or use PS.
> >

Actually there is another possibility.
Microsoft has just made a viewer application for Word 6.0 files
freely available for downloading. This would mean that anybody would
be able to read and print Word files (not just owners of MS Word).

Perhaps we could have some of the archive files available in this
format as an experiment.

If any of the authors of the archive diagrams wish to contact me,
I'll try and arrange to convert their diagram to Word 6.0 format.

P.S. This has an advantage, in that we will no longer need to break
the diagrams into multi-part files.

/-\ |_ /-\ |\|  Alan Light  alight@panix.com | History's third dimension
(finger alight@panix.com for PGP public key) | is always fiction.
                                             |  - Hermann Hesse





Date: Wed, 22 Feb 1995 14:28:41 -0400
From: hull@cs.uri.edu (Tom Hull)
Subject: Another conference!

Hello everyone!

     I've been asked to announce a conference for this summer which
will have an origami component. It's called

                Symmetry: Natural and Artificial
                 the 3rd International Congress
                             of the
           International Society for the Interdisciplinary
               Study of Symmetry (ISIS-Symmetry)

                       August 14-20, 1995
                     Old Town Alexandria, VA USA

According to the first circular:
     "The congress and exhibition present a broad interdisciplinary
forum where the representatives of various fields in art, science, and
technology may discuss and enrich their experience. The concept _symmetry_,
having roots in both art and science, helps to use a `common language'
for this purpose. The new `bridges' between disciplines could inspire
further ideas in the original field of participants, as well as
facilitate the adaptation of existing ideas and methods from one field
to another."

     Part of this conference will include a mini symposium on origami.
The organizers are looking for people (especially Americans) who would
like to lecture on origami for this symposium. Topics NEED NOT BE
RESTRICTED TO MATH! Both mathematicians, scientists AND artists
will be attending, so talks strictly on artistic methods or on
special origami techniques are also sought after.
     I highly encourage you all to think about participating! I
know I will!
        Contacts:  Denes Nagy: nagy@kafka.bk.tsukuba.ac.jp
                   Gyorgy Darvas: h492dar@ella.hu
                   Martha Pardavi-Horvath: pardavi@seas.gwu.edu

     Please email Denes Nagy ASAP if you're interested.

--------------- Tom "giggles, the knife!" Hull





Date: Wed, 22 Feb 1995 16:05:14 -0400
From: MLGerard@aol.com
Subject: Help with Ghostscript

Hello everyone,

I am having difficulty getting GhostScript to run on my PC (either the DOS or
Windows version).  The error message I get is something akin to:

error /undefined in gs
Operand stack:
Execution stack:  %interp_exit . . . .(foo, foo, foo and more foo)
Dictionary stack:. . . (more foo)
Current allocation mode is local
Current file position is 3

MGerard





Date: Wed, 22 Feb 1995 18:16:06 -0400
From: Joseph Wu <jwu@cs.ubc.ca>
Subject: Postscript vs. GIF (was: Re: Reading FTP files...)

On Tue, 21 Feb 1995, Kumar Patel wrote:

>       I don't have a postscript printer either (HP LaserJet III) and I
> doubt the majority of people who subscribe do.  I would use ghostscript,
> but it doesn't support my printer.  It's also a very large program (4
> megs) and I really don't have that much free space.  For me at least,
> GIF would definetly be easier.
>       As for print quality, I fail to see why this matters because
> they are "just line drawings".  Also, GIF is pretty much the Internet
> standard and most of the people out their have GIF viewers.  And,
> archiving our models in a universal format will attract many more
> uninitiated to this great art.

Print quality makes a big difference at 300 dpi (or higher). A PS file is
an image description file. Whatever you use to process that file
(Ghostscript, PS printer, whatever) will render that image to the best of
its ability at the highest resolution possible. A GIF file, however, is a
raster image file. That means that it stores every single pixel of the
final image. For an 8-1/2" x 11" image, that means 8415000 pixels at
300 dpi. Assuming standard GIF, which has 1 byte per pixel, you're
looking at almost 8.5 megabytes. GIF also performs compression, but even
at optimal compression of about 25%, you still have 2.1 megabytes.
Assuming that you could further reduce it to 1 bit per pixel, you finally
have a managable file at about 1/4 megabyte. But that's the size of most
PS files...

The other problem, once you have GIF images, is viewing them. There is
absolutely no way to view an 8-1/2" x 11" x 300 dpi image on a screen.
Not enough pixels. And printing it? Well, at 1 bit per pixel, you will
need over 1 MB of printer memory to print. However, I believe that most
printers take bitmap information in bytes rather than bits, so you will
need over 8 MB of printer memory to print!

See why PS is a good idea?

Joseph Wu      <jwu@cs.ubc.ca> | Witty quote is now back to the
Master's Student               |   drawing board due to squeamish
University of British Columbia |   readers. Any suggestions?
WWW: http://www.cs.ubc.ca/spider/jwu/origami.html (Origami Page)





Date: Wed, 22 Feb 1995 19:10:46 -0400
From: Tamar Schiller <aimee@free.org>
Subject: Re: Reading FTP files...

On Wed, 22 Feb 1995, Alan Light wrote:

>
> > >
> > > So... either use GIF and feel guilty or use PS.
> > >
>
> Actually there is another possibility.
> Microsoft has just made a viewer application for Word 6.0 files
> freely available for downloading. This would mean that anybody would
> be able to read and print Word files (not just owners of MS Word>
> /-\ |_ /-\ |\|  Alan Light  alight@panix.com | History's third dimension
> (finger alight@panix.com for PGP public key) | is always fiction.
>                                              |  - Hermann Hesse

Well, for those of you who have Windows (that's pretty much everyone),
the word processor, Write, which is pretty powerful, can read Word for
DOS files. (that's the .doc extention)
So, maybe it will work!

-aimee "the internet child (well, teen)"

aimee@free.org





Date: Thu, 23 Feb 1995 02:23:38 -0400
From: PIESCHT@delphi.com
Subject: Ghostscript

Sorry for the incomplete posting.  The ftp site for ghostscript is
ftp.cs.wisc.edu/ghost/aladdin.  The current version is 3.12.  It seems
to be available for various operating systems.  Besides the one for your
system, you need gs312ini.zip and gs312fn1.zip and gs312fn2.zip.  The last
two files are font files.  Also needed to view postscript files is the
ghostscript viewer at ftp.cs.wisc.edu/ghost/rjl/gsvw113.zip.  I hope this
is of some help.  Keep folding!
               Tim





Date: Thu, 23 Feb 1995 11:05:11 -0400
From: Rjlang@aol.com
Subject: Re: Jerry Harris is my hero!

> Jerry Harris's instructions for crimping and doing sinks were wonderful!
> I have reposted them separately for those that missed it the first time.
> ...[from Jerry]...Step 17 of Lang's "Nautilus" is NOT pleating!!!
> (Everyone get out their red pens and correct this).

Jerry's instructions were wonderful: however, his terminology was incorrect.
Since I already posted a somewhat longer exposition of the difference between
a crimp and a pleat I won't re-post the full description. However, the
essential difference between a crimp and a pleat is that in a pleat, all of
the layers of a flap are folded together, which in a crimp, some layers go
inside of others. Thus, Step 17 of the Nautilus is indeed a pleat, step 19 is
a crimp, and everyone can put away his red pen.

Robert





Date: Thu, 23 Feb 1995 11:55:08 -0400
From: Laurie_Reynolds@smec.sel.sony.com (Laurie Reynolds)
Subject: R. Lang's - Crimps and pleats

I thought that I'd repost this for completeness.  Will this and Jerry Harris's
instructions be made available on the archive?

Regards,
lr

On Monday, 13 Feb. Jerry Harris wrote:

> ...Step 17 of Lang's Nautilus is NOT pleating!!! (Everyone get out
> their red pens and correct this).

Well, I hope your red pens are not indelible, because step 17 of the Nautilus
is indeed a pleat. The essential difference between a crimp and a pleat lies
not the angle of the folds (more on this issue in a minute) but in the
configuration of the raw edges of the paper (or the edges that would be
exposed in a slice through the paper). In a pleat, all of the edges in the
flap go the same direction; in a crimp, different layers go different ways.
For example: in a two layered flap, look at the edges of the paper. If they
look like this:

--------
-----  /
    /  -----
   ------

it's a pleat. If they look like this:

--------
       /
      -------
      -------
       \
--------

it's a crimp.

John and I don't talk about crimps versus pleats in OSL but you can find a
fuller exposition of this distinction in Origami Zoo (Lang/Weiss) and Origami
Animals (Lang).

Now, for those who try to make the claim that it's a pleat if the lines are
parallel and a crimp otherwise, there are lots of pathological cases that
make that definition problematic (as well as less common in general usage).
For example, what happens if the angle of the lines differ by 0.000001
degree? Has it magically shed its pleat-ness and become a crimp due to that
extra nanoradian?

Also, although Jerry says that in a crimp, "the lines _do_ intersect," if the
mountain and valley folds are _nearly_ the same angle but are spaced apart
from one another, the point of intersection might be awfully far away from
the model!

Philosophically, if we're going to have two different terms in usage, then
they should describe two structures that differ by more than an infinitesimal
amount. In my, John's (and incidentally, quite a few other people's)
definition, crimps and pleats are fundamentally different; which is why step
17 is a pleat and step 19, which has creases in exactly the same place but
different layers go different directions, is a crimp.

(Definitions aside, Jerry gave a very good description of performing the
folds, whatever-they-are.)

Robert Lang

----- End Included Message -----





Date: Thu, 23 Feb 1995 12:21:06 -0400
From: Doug Philips <dwp+@transarc.com>
Subject: Best of Origami-L -- Articles in the Archive.

In message <9502231547.AA15634@sparky.smec.sel.sony.com>
    Laurie_Reynolds@smec.sel.sony.com (Laurie Reynolds) wrote:
+I thought that I'd repost this for completeness.  Will this and Jerry Harris's
+instructions be made available on the archive?

All the messages sent to origami-l are captured in the archive maintained by
the list server at nstn.ca.  Ftp to nstn.ca, login as anonymous and cd to
/listserv/origami-l.  For reasons which no one seems to understand, recent
archives are often protected so that you can't read them.  If that happens,
drop a note to daniel@nstn.ca and ask for them to be unprotected.
Alternatively, there is also an archive of origami-l messages on
rugcis.rug.nl (or info.service.rug.nl, I'm not sure which is the "proper"
name to use).  Login as anonymous and cd to /origami/archives.

But I think that isn't the answer you were looking for.  While it is true that
those articles are in the archives, they are buried with the stream of all the
saved articles and have to be hunted for.

I wouldn't mind seeing a separate archive of "The Best of Origami-l" or
"Gems from Origami-l" or some other such thing.  Whatever it was called, it
would be a collection of the most informative/definitional (or some other as
yet unarticulated criteria) articles from origami-l.  (I would even be willing
to work on it, but not if no one else is interested. ;-) ).

-Doug





Date: Thu, 23 Feb 1995 13:02:16 -0400
From: Laurie_Reynolds@smec.sel.sony.com (Laurie Reynolds)
Subject: Re: Best of Origami-L -- Great idea!.

Hi Doug,

As I was writing the mail asking about availability of info on the archive,
i thought "naturally it is archived, but as you mentioned it's buried into
obscurity".

It would be infinitely more useful if there were categories:
ie:     model instructions
        general instructions
        resources

Cheers,
lr





Date: Thu, 23 Feb 1995 14:49:29 -0400
From: Joseph Wu <jwu@cs.ubc.ca>
Subject: Re: Best of Origami-L -- Articles in the Archive.

On Thu, 23 Feb 1995, Doug Philips wrote:

> I wouldn't mind seeing a separate archive of "The Best of Origami-l" or
> "Gems from Origami-l" or some other such thing.  Whatever it was called, it
> would be a collection of the most informative/definitional (or some other as
> yet unarticulated criteria) articles from origami-l.  (I would even be willing
> to work on it, but not if no one else is interested. ;-) ).

Sounds good. I'd be interested in seeing it, and maybe even helping with
it (AFTER April, when my thesis is completed).

Joseph Wu      <jwu@cs.ubc.ca> | Witty quote is now back to the
Master's Student               |   drawing board due to squeamish
University of British Columbia |   readers. Any suggestions?
WWW: http://www.cs.ubc.ca/spider/jwu/origami.html (Origami Page)





Date: Thu, 23 Feb 1995 15:05:22 -0400
From: Laurie_Reynolds@smec.sel.sony.com (Laurie Reynolds)
Subject: Re: Best of Origami-L -- Who'll pay.

Sheldon Ackerman wrote:

------------------------------------------------------

>
> As I was writing the mail asking about availability of info on the archive,
> i thought "naturally it is archived, but as you mentioned it's buried into
> obscurity".
>
> It would be infinitely more useful if there were categories:
> ie:   model instructions
>       general instructions
>       resources

And who is going to get paid to do that job?

---
Sheldon Ackerman
ackerman@dorsai.dorsai.org
sheldon.ackerman@nycps.nycenet.edu

-----------------------------------------------------------

I am sorry, but I was responding to the mail by Doug Philips, and should have
included it in my previous email.   He was volunteering to address the issue.
I was not suggesting that it be done, but merely agreeing with Doug in that it
would be useful.
-----------------------------------------------------------

An excerpt of what Doug wrote

.......................

I wouldn't mind seeing a separate archive of "The Best of Origami-l" or
"Gems from Origami-l" or some other such thing.  Whatever it was called, it
would be a collection of the most informative/definitional (or some other as
yet unarticulated criteria) articles from origami-l.  (I would even be willing
to work on it, but not if no one else is interested. ;-) ).

-Doug

=========================

sorry :-(

lr





Date: Thu, 23 Feb 1995 17:02:20 -0400
From: John_Marcolina@Strata.COM (John Marcolina)
Subject: Seeking Grand Piano Diagrams

Hello all,
This is my first contribution to this list (I've been listening for awhile).
I've been folding on and off for almost twenty years, and I have a passion
for realistic folds (which often turn out to be the most complex). I've
amassed a large library of books (my favorites are by Lang, Montroll, and
Engel), but I've never come across Patricia Neal's Grand Piano, which I've
seen in pictures. Does anyone know if there is a book currently in
publication in which it appears?
Alternatively, if there is anyone out there who has the diagrams and would
like to share them with me, I would happily cover the cost of postage. A FAX
would also work.

Thanks in advance,
John Marcolina
jrm@strata.com





Date: Thu, 23 Feb 1995 21:28:55 -0400
From: jdharris@teal.csn.net (Jerry D. Harris)
Subject: Re: Jerry Harris is my hero!

>> Jerry Harris's instructions for crimping and doing sinks were wonderful!
>> I have reposted them separately for those that missed it the first time.
>> ...[from Jerry]...Step 17 of Lang's "Nautilus" is NOT pleating!!!
>> (Everyone get out their red pens and correct this).
>
>Jerry's instructions were wonderful: however, his terminology was incorrect.
>Since I already posted a somewhat longer exposition of the difference between
>a crimp and a pleat I won't re-post the full description. However, the
>essential difference between a crimp and a pleat is that in a pleat, all of
>the layers of a flap are folded together, which in a crimp, some layers go
>inside of others. Thus, Step 17 of the Nautilus is indeed a pleat, step 19 is
>a crimp, and everyone can put away his red pen.
>
>Robert

Robert et al -

        Hmmmmm...I never thought about it that way; to me, the big
difference between a pleat and a crimp has _always_ been whether or not the
fold lines connect.  Thus, there are pleats, crimps, inside crimps, and
outside crimps (the latter two really depending on which portion of the
model in question is remaining static in the diagram), not just merely
pleats and crimps.

        The word "pleat" is a Middle English term derived from the
antiquarian "plait" and forms thereof; it is defined, really, as a fold in
cloth made by doubling material over on itself.  True, this definition
technically doesn't say that all the fold lines are parallel; in this, you
are correct in your definitions of the two fold types, and mine is
different.  However, the term "crimp" is from the German/Dutch tradition,
and is defined as "to cause to become wavy, bent, or warped."  The terms
warped, bent, and wavy do not, IMHO, call to mind nice, symmetrical,
parallel lines...after all, when was the last time you saw a piece of wood
warp like a paper fan?  No, these terms describe angularity -- lines that
intersect at some point.

        So, if then we have a nice definition of crimp, we must now
differentiate them from pleats.  Really, pleats could be called a "subset"
or "subtype" or crimp -- pleats are a special kind of crimp, in which all
the lines are parallel.  It is similar to the situation with the definition
of a "square":  a square is simply a rectangle that happens to have all
four sides of equal length.  Squares are a "subset" of rectangle.  But it
would be confusing, in origami, to refer to both "pleats" and "crimps" (no
matter the definition!) all as "crimps!"

        Under your definition of crimp, more than one layer of paper is
always involved...it neglects the (admittedly rarely used) example as I
described in my initial letter, where a single layer of paper is folded via
two lines which intersect at the edge of the paper.   Is this, then, a
pleat?  Clearly it's different than folding a series of parallel lines --
in fact, I can easily teach anyone to pleat a series of parallel lines, but
virtually everyone I've ever taught has a really difficult time with crimps
of any sort, whether they be with a single flap or several!

        Essentially, I just advocate retaining the usage of such terms as
"inside crimp" and "outside crimp," as opposed to dumping them into the
wastebasket in favor of just "crimp," since a "crimp" on a single layer of
paper is different than performing a move in which several layers of paper
are "crimped" inside or outside others.  It was this realization that led
me to ponder just what defines a crimp; the intersection of the fold lines
is absolutely common to all crimps (regular, inside, and outside); pleats
are different in that they do not share this feature (can you tell I'm a
systematics scientist?!?  ;-)  )

Jerry D. Harris
Denver Museum of Natural History
2001 Colorado Blvd.
Denver, CO  80205
(303) 370-6403

Internet:  jdharris@teal.csn.net
CompuServe:  73132,3372

--)::)>   '''''''''''''/O\'''''''''''`  Jpq--   =o}\   w---^/^\^o

OOO f the Earth's many creatures, not all did survive.
O   O Only those that adapted are today still alive!
OOO Those that couldn't -- or wouldn't -- are with us no more:
The most famous of these is the great dinosaur!
"Evolution," they call it; a 10-dollar word.
That's how nature, in time, from a fish, made a bird.

                                                -- Martin J. Giff

--)::)>   '''''''''''''/O\'''''''''''`  Jpq--   =o}\   w---^/^\^o
