yet another claim about flowing window glass
Jeffrey Shallit
Here's yet another sighting of the "window glass flows like a liquid,
that's why window panes in old houses are thicker at the bottom"
urban myth:
"For example, glass window panes in 17th and 18th century
U.S. homes are thick at the bottom and often have a gap at the top,
because the glass, a very high viscosity fluid, has been very
slowly flowing downward under the influence of gravity."
-- Brooks B. Ellwood, _Geology and America's National Park Areas_,
Prentice-Hall, 1996, p. 138.
Jeffrey Shallit, Computer Science, University of Waterloo,
Waterloo, Ontario N2L 3G1 Canada sha...@graceland.uwaterloo.ca
URL = http://math.uwaterloo.ca/~shallit/
Peter Ceresole
In article <EB9EG...@undergrad.math.uwaterloo.ca>,
sha...@graceland.uwaterloo.ca (Jeffrey Shallit) wrote:
> "For example, glass window panes in 17th and 18th century
> U.S. homes are thick at the bottom and often have a gap at the top,
> because the glass, a very high viscosity fluid, has been very
> slowly flowing downward under the influence of gravity."
>
> -- Brooks B. Ellwood,
Oh heck, Brooks Ellwood, of course, we go back a long way. He was a student
in London and we both used to do a holiday job that involved going round
the London shops at night in summer (when the temperatures are high and
glass flow is at it's greatest) rectifying plate glass windows that had
sagged and flowed during the day. I gave an account of this work here last
year. Anyway, this is probably what gave him the idea for this part of his
book.
Fancy that.
--
Peter
Peter Ceresole
In article <AFBC1A67...@cara.demon.co.uk>,
pe...@cara.demon.co.uk (Peter Ceresole) wrote:
>when the temperatures are high and
>glass flow is at it's greatest
Goddam, how did I come to write that? Of course it's "its".
--
Peter
Johann Junginger
Since we're on the topic, here's a story I'd been meaning to share for
quite while but didn't want to bring up for fear of incurring the wrath of
a.f.s.
I was procrastinating in the physics student lounge one fine afternoon
this past winter, when someone mentioned something about broken glass. I
immediately quipped something to the effect of "glass doesn't break; it's
a liquid so it flows". I was expecting numerous jeers but instead a huge
discussion (discussion, NOT debate) broke out with everyone agreeing and
bringing up anecdotes of windows in old houses and all the "proofs" we
know so well.
To my dismay, one of the most vocal proponents of the flowing glass theory
was a graduate student who was in the midst of writing her thesis in
condensed matter physics.
My classmates where all so convinced I didn't have the heart (nor the
patience) to explain the error of their ways and refer them to this
newsgroup. I left in disgust.
I have noticed a similar phenomenon when I discuss my favourite urban
legends. I clearly start out by mentioning that these are established
urban legends and then go into the details. Inevitably, someone will pipe
up and say "No, it's true! It happened to a FOAF at work. <Perfectly
serious and horrified> But have you heard about... <Insert favourite UL
here>".
Will do physics for food,
Yohaun.
--
\|/ Imagine this living carcass, screaming. \|/
-- * -- screaming endlessly into the anechoic void... -- * --
/|\ /|\
Illtud Daniel
DaveHatunen <hat...@netcom.com> wrote:
>The "gap at the top" is something new, I think. I've never heard it
>before.
I've seen it claimed here before. (~2 yrs ago?)
--
Illtud Daniel ida...@jesus.ox.ac.uk
-see Twin Town- -Buy Apollo 440-
Peter Ceresole
In article <5n8ntl$s...@news.ox.ac.uk>,
ida...@jesus.ox.ac.uk (Illtud Daniel) wrote:
>I've seen it claimed here before. (~2 yrs ago?)
Hasn't it been claimed *every* year? Last, if I remember right, in
connection with European Cathedral windows. Living in Europe and having
visited a whole slew of cathedrals, I remember posting an amazed rebuttal-
where *do* people go to get these ideas?
In fact this recurring thread is one of the finest examples of human
gullibiity and tendency to shoot from the mouth without aim or evidence.
It's what the newsgroup is about, really. I rather treasure it.
--
Peter
RM Mentock
Peter Ceresole wrote:
> In fact this recurring thread is one of the finest examples of human
> gullibiity and tendency to shoot from the mouth without aim or evidence.
Do you have a citation for that?
> It's what the newsgroup is about, really. I rather treasure it.
--
D.
men...@mindspring.com
http://www.mindspring.com/~mentock/index.htm
Drew Lawson
In article <AFBDDB28...@cara.demon.co.uk>, pe...@cara.demon.co.uk
(Peter Ceresole) wrote:
> In article <5n8ntl$s...@news.ox.ac.uk>,
> ida...@jesus.ox.ac.uk (Illtud Daniel) wrote:
>
> >I've seen it claimed here before. (~2 yrs ago?)
>
> Hasn't it been claimed *every* year? Last, if I remember right, in
> connection with European Cathedral windows. Living in Europe and having
> visited a whole slew of cathedrals, I remember posting an amazed rebuttal-
> where *do* people go to get these ideas?
Perhaps you should read more carefully.
The "glass flows" claim is repeated endlessly. But the claim that
old windows have a *gap* at the top is not. In fact it is often
offered as a rhetorical question to the Believers, "How many of those
windows have flowed away from the frame at the top?"
Drew "flow, flow, flow your boat" Lawson
--
Drew Lawson | I have no genitalia
dla...@aimnet.com | I sold my kids for cheese
| I love my blow-up doll, so
www.aimnet.com/~dlawson | bring out those cameras, please
Rick Tyler
On Thu, 05 Jun 1997 16:37:08 +0100, pe...@cara.demon.co.uk (Peter
Ceresole) wrote:
:In article <AFBC1A67...@cara.demon.co.uk>,
:pe...@cara.demon.co.uk (Peter Ceresole) wrote:
:
:>when the temperatures are high and
:>glass flow is at it's greatest
:
:Goddam, how did I come to write that? Of course it's "its".
:
Its KO, Peter. AFU won't kill there own for making a speling misteak.
Their more forgiving they're then that.
-- Rick the Typgni Dylscixe
-----------------------------------------------
Try www.urbanlegends.com for the straight dope.
Peter Ceresole
In article <dlawson-0706...@news2.aimnet.com>,
dla...@aimnet.com (Drew Lawson) wrote:
>Perhaps you should read more carefully.
>
>The "glass flows" claim is repeated endlessly. But the claim that
>old windows have a *gap* at the top is not.
You are wrong. The "gap at the top" comes up at least once per cycle. And
as I said, last time was in connection with cathedral windows.
--
Peter
Andrew Reid
Johann Junginger wrote:
> To my dismay, one of the most vocal proponents of the flowing glass theory
> was a graduate student who was in the midst of writing her thesis in
> condensed matter physics.
>
Well, this is perhaps a trifle unfair. As I enjoy carping about
at length, one cannot make a robust conclusion about glass flow
on the basis of currently understood physical principles. Some
amorphous substances flow, some don't, some crystalline substances
are awfully soft, others are spectacularly hard, and the reasons
have to do with the details of the chemistry, and sometimes the
thermal or mechanical history of the substance in question.
In order to know whether or not glass flows, you have to
go out and measure some, or read about a credible, repeatable
experiment where a clear result was obtained. It's perfectly
reasonable for a graduate student in condensed-matter physics, or
even materials science, never to have done this.
Any scientist, of course, should have a healthy respect
for the results that *are* obtained from credible, repeatable
experiments, and all of these clearly show that ordinary glass
under ordinary conditions doesn't flow.
Andrew "Here we go again..." Reid
Brian Mueller
The Great and Exhalted Peter Ceresole wrote:
>In fact this recurring thread is one of the finest examples of human
>gullibiity and tendency to shoot from the mouth without aim or evidence.
>It's what the newsgroup is about, really. I rather treasure it.
Well in the end, calling glass a solid or a liquid at normal
temperatues is a semantic thing. Obviously it doesn't flow enough for
evidence to be visible in church windows (or roman glass). Now, if
there were a piece of (very old, at least 40,000 years) volcanic
glass, the age and original shape (the second criterium is very
important) of which were known, the flow might be readily apparent.
In reality, however, glass is clearly liquid over L O N G timescales,
that is, long in terms of the age of the earth or that of the
universe. In other words, a materials scientist will call glass a
solid but a physicist should not (because over the timescales with
which physics is familar, glass is quite liquid).
DaveHatunen
In article <339f596c...@nntp.ix.netcom.com>,
There is penty of obsidian around which would clearly show flow if flow
occurred. It does not. How to tell? Sharp edges cannot remain sharp in
substances that flow.
Since physicists have little reason to deal with glass over the
timescales you mention, a cite would certainly be appreciated. Almost
all cites of a suposed viscosity of glass at STP are specifying a
minimum viscosity. Thsi is rather like the way the size of the electron
is stated to be a maximum of x, when some surmise the electron is a
point.
--
********** DAVE HATUNEN (hat...@netcom.com) **********
* Daly City California: *
* where San Francisco meets The Peninsula *
* and the San Andreas Fault meets the Sea *
*******************************************************
Peter Ceresole
In article <339E3D...@jetson.uh.edu>,
jmoore <jwm9...@jetson.uh.edu> wrote:
>Has anyone contributed the concept of creep to this thread? In Material
>Science, its a phenomenon where materials (even solids) are seen to
>deflect over time when acted on by a constant force.
Any gas turbine wallah will confirm that creep in blade materials at their
operating temperatures (which are well short of liquid phase) is a serious
consideration. Of course these are crystalline metals; I guess that in that
case *everything* is liquid, including glass.
Maybe we've solved the problem?
--
Peter
Ray Depew
jmoore (jwm9...@jetson.uh.edu) wrote:
: Has anyone contributed the concept of creep to this thread? In Material
: Science, its a phenomenon where materials (even solids) are seen to
: deflect over time when acted on by a constant force.
That's a good point.
Yes, actually, the concept of creep was invoked last time this thread
went around, to argue that metals "flow" faster than glasses do. We
know creep and flow are different phenomena, but they both involve
permanent deformation of a solid.
Thanks for bringing it up, though.
Regards
Ray Depew
Ian A. York
In article <339f596c...@nntp.ix.netcom.com>,
Brian Mueller <muld...@ix.netcom.com> wrote:
>
>In reality, however, glass is clearly liquid over L O N G timescales,
>that is, long in terms of the age of the earth or that of the
>universe. In other words, a materials scientist will call glass a
If it's that clear, would you mind running the calculations? Researchers
from the Corning Museum of Glass have told me that
... according to a computer model, over millions of years, a large sheet
of glass hanging vertically would gain only a few molecules of extra
thickness on its lower surface.
(Unfortunately, the paper is not yet published, so I can't give all the
details.)
So at first glance there is a possible truth to the "liquid over billions
of years" claim.
But wait! Glass crystallizes! So if we're dealing with reality then we
have to ask whether there will be any detectable flow before the glass has
crystallized; and the answer is, as far as I can see, that there will not
be any. I understand (Charles "Wham" Dimmick, please feel free to leap
in) that obsidian in the glassy state is considered by geologists to be,
automatically, "young", because "old" obsidian is no longer in a glassy
state.
In other words, I think your contention is still pretty iffy, if you're
talking about a real world. And if you're *not* talking about a real
world, but rather some imaginary Platonic world where glass doesn't
crystallize, then you've arbitrarily chosen to ignore one property og
glasses but not another.
Ian
--
Ian York (iay...@panix.com) <http://www.panix.com/~iayork/>
"-but as he was a York, I am rather inclined to suppose him a
very respectable Man." -Jane Austen, The History of England
Barbara Mikkelson
In alt.folklore.urban jmoore <jwm9...@jetson.uh.edu> wrote:
> Has anyone contributed the concept of creep to this thread?
Rec.org.mensa has done its bit -- they'd tried to hand off as many creeps
as we'd take.
Barbara "we smiled, said 'thank you!'... and packed the lot of them off
to alt.usage.english" Mikkelson
--
| I was sorely tempted to give the preceding
Barbara Mikkelson | information in haiku form, but after Jennifer
bmik...@fas.harvard.edu | Mullen's recent experience I (wisely) decided
| against it. - Michele Liguori
------------------------------------------------------------------------
View a random urban legend --> http://www.snopes.com/cgi/randomul.cgi
Lizz Braver
In article <339E3D...@jetson.uh.edu>, jwm9...@jetson.uh.edu says...
>Has anyone contributed the concept of creep to this thread? In
Material
>Science, its a phenomenon where materials (even solids) are seen to
>deflect over time when acted on by a constant force.
> Bender
I have noticed many creeps posting to this thread--generally ones that
are too lazy to read the many references posted by Dr.Ian York.
Please don't become one of them.
Lizz "Committee to Re-invent the Present" Braver
RM Mentock
Ronda Bandy wrote:
>
> <snip because am not sure who wrote this>
>
> > Good point. Two or three glass-flow-debate cycles ago, I brought up
> > the Obsidian Cliff(s), in Yellowstone National Park, USA. This geographic
> > feature is made of polygon-shaped columns of obsidian, some huge number
> > of feet high. (The first time I saw the cliffs, I was reminded of the
> > basalt columns of the Devil's Causeway in Scotland.) If glass really
> > flowed, one would expect to see some bulging, puddling, dripping or other
> > evidence of flow along the cliffs. Instead, all one sees are huge piles
> > of talus around the base, and the normal weathering one would expect to
> > see in rock that many thousand? million? years old. No signs of "glass
> > flow" at all.
>
> If I am correct on the structures you are talking about, (ie Devil's
> Tower) I believe this is what is left of the lava from inside a volcano.
> The volcano itself has weathered away. I could be wrong, but I don't
> believe hardened lava is glass. Is it? Either way, have never heard of
> it or glass flowing. Guess it's OT. :))
Devil's Tower is a supposed volcanic plug whose sides are huge
columns (it was the featured icon in Close Encounters of the Third
Kind). It is in North*east* Wyoming. The Obsidian cliffs of
Yellowstone are in North*west* Wyoming and they are not the same thing.
Minerals have different chemical makeup, but the same makeup can
produce "rock" or glass depending upon the cooling sequence. Glass
is formed when the material is quenched quickly (geologically
speaking).
Jim Everman
All due respects, but have people quit reading?..
> > > Good point. Two or three glass-flow-debate cycles ago, I brought up
> > > the Obsidian Cliff(s), in Yellowstone National Park, USA.
> > If I am correct on the structures you are talking about, (ie Devil's
> > Tower). . .
> Do you mean the "Giant's causeway" in Ireland?
--
Jim Everman eve...@Anet-STL.com
Never attribute to malice what can be adequately explained by
stupidity.
Colin Dooley
Ronda Bandy wrote:
>
> <snip because am not sure who wrote this>
>
> > feature is made of polygon-shaped columns of obsidian, some huge number
> > of feet high. (The first time I saw the cliffs, I was reminded of the
> > basalt columns of the Devil's Causeway in Scotland.) If glass really
> > flowed, one would expect to see some bulging, puddling, dripping or other
> > evidence of flow along the cliffs. Instead, all one sees are huge piles
> > of talus around the base, and the normal weathering one would expect to
> > see in rock that many thousand? million? years old. No signs of "glass
> > flow" at all.
>
> The volcano itself has weathered away. I could be wrong, but I don't
> believe hardened lava is glass. Is it? Either way, have never heard of
> it or glass flowing. Guess it's OT. :))
Do you mean the "Giant's causeway" in Ireland?
This is indeed columns of Basalt formed by volcanic activity.
Ref: Microsoft Encarta
--
<\___/> | Rules for Academic Deans:
/ O O \ | (1) HIDE!!!!
\_____/ FTB. | (2) If they find you, LIE!!!!
-- Father Damian C. Fandal
Michael Naunton
On Sat, 14 Jun 1997 18:09:37 GMT, Joe Deinet <jde...@shentel.net> wrote:
>
>
>In my original posting some time ago I stated that glass was a liquid,
And you were wrong
>but that it could not be observed to flow in a short period of time.
Because it doesn't flow.
>It is somewhat difficult for the scientifically impaired to
>understand.
As are creationism, n-rays, etc.
> I suggest that anyone doubting this find someone who has
>studied physics or advanced physical chemistry at some university and
>have this explained.
Many of the poeple responding to you have studied these subjects in
college.
> For those who have access to Compton's
>Interactive Encyclopedia '97 please look under glass.
CIE is a poular, secondary source. Look at the actually papers, I doubt
you will find one that states that glass flows at room temperature.
>It states that
>glass is a supercooled liquid which most physicists call an extremely
>viscous liquid. Unlike ordinary solids, glass belongs to a class os
>substances which do not have a true melting point, but simply start to
>flow more rapidly as the temperature is raised.
It is a non-crystaline solid. Many supercooled liquids are called solids,
e.g. steel.
>The main conflict here seems to be the difference in definition of
>what constitutes a liquid as understood by a scientist as opposed by a
>non-scientist.
A number of scientists have weighed in on this topic. Points brought up
include obsidian rock formations, old telescope lens showing no evidence of
deformation, and Eyptian glass scarabs showing no flow.
As an aside, my (scientist) wife has spent the last year
restoring old (thousand year plus) glass artifacts at the Metropolitan
Museum of Art. She pointed out a number of ways in which old glass
degrades, but flow was not one of them.
Read the FAQ,
Regards,
M Naunton.
Ian A. York
In article <5numrj$5sh$1...@marshall.shentel.net>,>understand. I suggest that anyone doubting this find someone who has
>studied physics or advanced physical chemistry at some university and
>have this explained.
Been there. Done that. They agree that glass ain't a liquid.
You will note that the following references are written by people who are
not exactly "scientifically impaired".
There is an article by Florin Neumann at
<http://www.ualberta.ca/~bderksen/florin.html> which cites in its
debunking of this legend the following references:
Doremus, R. H. (1994) Glass Science, 2nd Edition. John Wiley & Sons, New
York, 339 pp. ISBN 0471891746.
Elliott, S. R. (1994) Amorphous Solids: An Introduction. In: Catlow, C. R.
A. (eds.), "Defects and Disorder in Crystalline and Amorphous Solids",
NATO Advanced Studies Institutes Series; Series C, Mathematical and
Physical Sciences, 418, Kluwer Academic Publishers, Dordrecht: 73-86.
ISBN 0792326105.
Feltz, A. (1993) Amorphous Inorganic Materials and Glasses. VCH
Verlagsgesellschaft mbH, Weinheim/VCH Publishers, New York, 446 pp. ISBN
3527284214/1560812125.
Gutzow, I. and Schmelzer, J. (1995) The Vitreous State: Thermodynamics,
Structure, Rheology, and Crystallization. Springer Verlag, Berlin, 468 pp.
ISBN 0387590870.
Jeanloz, R. and Williams, Q. (1991) Solid-State Physics: Glasses Come to
Order. Nature, 350: 659-60.
Pfaender, H. G. (1996) Schott Guide to Glass, 2nd Edition. Chapman & Hall,
London, 207 pp. ISBN 0412719606.
Plumb, R. C. (1989) Antique windowpanes and the flow of supercooled
liquids. Journal of Chemical Education, 66(12): 994-996.
Rawson, H. (1991) Glasses and Their Applications. Royal Institute of
Metals Book, Royal Institute of Metals, London, 499: 166 pp. ISBN
0901462896.
Tammann, G. (1933) Der Glaszustand. Voss, Leipzig, 123 pp.
One of those references (Antique windowpanes and the flow of supercooled
liquids. Robert C. Plumb. The Journal of Chemical Education 66(12),
994-6, 1989) is available in full at
<http://www.ualberta.ca/~bderksen/windowpane.html>). It in turn cites
other peer-reviewed refences in its debunking:
1. Tolman, C.A.; Jackson, N. B. In Essays in Physical Chemistry;
Lippincott, W. T. Ed.; Am. Chem. Soc.: Washington, DC, 1988; Chapter 3.
2. Ernsberger, F. M. In Glass: Science and Technology; Uhlmann, D. R.;
Kreidle, N. J., Eds.; Acad.: New York, 1980; Vol. V, Chapter 1.
3. Slater, J. C. Introduction to Chemical Physics; McGraw-Hill: New York,
1939; p 456.
4. Douglas, R. W. Brit. J. Appl. Phys. 1966, 17, 435-448.
5. Hall, J. A.; Leaver, V. M. J. Sci. Inst. 1961, 38, 178-185.
6. Holloway, D. G. The Physical Properties of Glass; Wykeham: London,
1973; pp 131-143.
7. Muspratt, S. Chemistry Theoretical, Practical & Analytical as Applied
and Relating to the Arts and Manufactures; Mackenzie: London, 1860; Vol.
II, pp 21-216.
8. Chance, H. J. Soc. Arts 1856, 4, 222-231.
One of these references (Ernsberger, F. M. In Glass: Science and
Technology; Uhlmann, D. R.; Kreidle, N. J., Eds.; Acad.: New York, 1980;
Vol. V, Chapter 1.) explicitly says:
There is a widespread opinion that glasses are supercooled liquids and
therefore have a finite viscosity at ordinary ambient temperatures.
Stories are told of glasses flowing under their own weight: of ancient
windowpanes that are thicker at the bottom; of glass that has sagged in
storage. These observations must find other explanations, because
glasses of commercially useful compositions are in fact rigid solids at
ordinary temperatures.
More:
Glass is an amorphous solid. A material is amorphous when it has no
long-range order, that is, when there is no regularity in the
arrangement of its molecular constituents on a scale larger than a few
times the size of these groups. ... A solid is a rigid material; IT DOES
NOT FLOW WHEN IT IS SUBJECTED TO MODERATE FORCES. More quantitatively, a
solid can be defined as a material with a viscosity of more than about
10^15 P (poises). --Doremus, Glass Science, 1973
The highest observed macro stress level acheived is only 20% of that,
and was done to a glass fiber (as close to flawless as we can get).
Therefore, we can not apply a yield stress to the glass that could cause
it to flow without first breaking our sample. If, somehow, magically,
you could apply a stress to an unflawed sample, then the observed
plastic deformation (e2) would be roughly 1/15000 the magnitude of the
applied stress (in kg/mm^2). So even if you could magically apply a
yielding stress, then you would not be able to measure the deformation.
This applies to glasses below 600C (or 270C for infinite time lengths).
--Elastic-Plastic Problems, B.D. Annin and G.P. Cherepanov, c 1988, The
American Society of Mechanical Engineers (paraphrased by Scott
Sehlhorst)
We use glass in this case, not because it is transparent, but because
its rigidity and permanence of shape are better than steel or concrete.
--Preston, J. Appl. Phys. (13) pp623-654, 1942
1. "A glass is an amorphous solid which exhibits a glass transition"
2. "A solid is a material whose shear viscosity exceeds 10^14.6
poise" --Physics of Amorphous Materials_ by S. R. Elliott (London:
Longman Group Ltd, 1983; ISBN 0-582-44636-8), from the definitions
section, p. 5
There's only one article that even remotely supports your contention, and
its very support actually refutes it, because it concludes that glass
could only flow if several real-world considerations were ignored: ou'd
have to have a piece of glass several miles long to observe any flow, and
it would take several million years for the effect to manifest itself.
They dismiss with a wave of their hands the objection that a piece of
glass that huge would crumble under its own weight, destroying the
evidence in much less than a million years . ("Gravity-Induced Flow of a
Structural Glass at Zero Temperature", by Clare C. Yu and S. N.
Coppersmith, from Journal of Non-Crystalline Solids, 131-133, 1991, pp
476-478). This is taken from Ray Depew's comments on the article; use
DejaNews to find the whole thing.
Further, the claim that people make to support their contention--that old
windows are thicker at the bottom--is trivially refuted, and so there is
no evidence that glass does flow. Two people in the past couple of weeks
in this thread have actually gone and looked at the windows in their old
houses, or their old cathedrals. Stephen Tonkin
<as...@aegis1.demon.co.uk> determined that "it is twaddle. In the
buildings I looked at many, but not all, of windows of uneven thickness
have the thicker glass at the bottom. Some have it at the side. A few
have it at the top." Charles Dimmick (dim...@ccsu.ctstateu.edu) said
"The south-facing windows of St. Peter's Church, Cheshire, Connecticut,
built in 1840, have panes that undulate, as though they had flowed. The
problem is that while most of the panes have undulations that would
indicate downward flow, 1/6 of the panes have undulations that would
indicate sidewards flow, and a few of the panes have undulations that
would indicate flow at 45 degrees to straight down." They therefore agree
with medieval stained-glass-window restorer Peter Gibson, who said that
"in a lifetime of dismantling medieval glass [windows] he had seen
hundreds of pieces that were thicker at the top."
This also agrees with the interpretation that the irregularity of the
glass is due to the Crown glass manufacturing method, as described in
(Muspratt, S. Chemistry Theoretical, Practical & Analytical as Applied
and Relating to the Arts and Manufactures; Mackenz)ie: London, 1860; Vol.
II, pp 21-216) by Sheridan Muspratt.
These are not all the references available that debunk this particular
legend. You can find more at
<http://www.urbanlegend.com/science/glass.flow>.
The sci.physics FAQ at <http://www.weburbia.com/physics/glass.html> also
debunks this legend.
Jim Everman
> > I suggest that anyone doubting this find someone who has
> >studied physics or advanced physical chemistry at some university and
> >have this explained.
>
> college.
Well, I have a degree in physics and I think that glass is a liquid
with a viscosity so damn high that, for all practical purposes, IT
DON'T F***ING FLOW! OK?
Jerry Bauer
>but that it could not be observed to flow in a short period of time.
> For those who have access to Compton's
>glass is a supercooled liquid which most physicists call an extremely
>viscous liquid.
Well, folks, there it is. On 5/13/97 I warned y'all about this particular
reference work and what it says about glass.
Jerry "I told ya so!" Bauer
Joe Deinet
In my original posting some time ago I stated that glass was a liquid,
but that it could not be observed to flow in a short period of time.
It is somewhat difficult for the scientifically impaired to
understand. I suggest that anyone doubting this find someone who has
studied physics or advanced physical chemistry at some university and
have this explained. For those who have access to Compton's
Interactive Encyclopedia '97 please look under glass. It states that
glass is a supercooled liquid which most physicists call an extremely
viscous liquid. Unlike ordinary solids, glass belongs to a class os
substances which do not have a true melting point, but simply start to
flow more rapidly as the temperature is raised.
The main conflict here seems to be the difference in definition of
what constitutes a liquid as understood by a scientist as opposed by a
non-scientist.
Joe
Lee Rudolph
jde...@shentel.net (Joe Deinet) writes:
>In my original posting some time ago I stated that glass was a liquid,
>but that it could not be observed to flow in a short period of time.
>It is somewhat difficult for the scientifically impaired to
>understand.
You ain't kidding, sonny. Look, your feeble trolls are growing
wearisome. Why don't you kindly fuck off and die, instead?
>The main conflict here seems to be the difference in definition of
>what constitutes a liquid as understood by a scientist as opposed by a
>non-scientist.
Yeah, right. Go away. Just *go* *away*.
Lee "patience impaired" Rudolph
Ben Monreal
On Wed, 11 Jun 1997, jmoore wrote:
> Has anyone contributed the concept of creep to this thread? In Material
> Science, its a phenomenon where materials (even solids) are seen to
> deflect over time when acted on by a constant force.
> Bender
WARNING: This is one very long, hopefully very clear post which tries to
clear up the whole debate, starting with the basics.
Creep, for those who aren't familiar, is the permanent bending of a
material under a comparatively weak force and a really long timescale.
For example, if you put a load on a piece of metal - say, for example,
take a long wire and hang a weight from the end - the metal will stretch
slightly. If the load was below a certain limit (corresponding to the
"tensile stregnth"), when you detach the weight, the wire will go back to
its original legnth. This is elastic deformation. If the weight
corresponded to a load _above_ the tensile stregnth, the wire will have
permanently deformed, even after the weight is removed. This is plastic
deformation.
Now, if you go back to the lighter weight (the one that did not
permanently deform the wire) and leave it hanging for a really long time,
you will find the wire to have stretched permanently and irreversibly.
This is known as creep ... plastic deformation under a constant
stress below the tensile stregnth. The elongation over time is called the
"creep rate", and it is related to the temperature, the exact material
properties, and the load.
<begin relevance to this thread here>
Aaaaaaanyway, so this will (pretty much) also happen to glass, everyone's
favorite amorphous material. If you have a piece of glass with a load on
it (for example, a window-pane supporting its own weight) it will indeed
deform. Probably microscopically, even over centuries ... creep rates at
room temperature tend to be very, very low. So low, in fact, that
materials scientists who have to measure creep rates always do it at high
temperatures (100s of degrees F) so that they don't spend a decade waiting
for one result. But yeah, you can easily envision a window pane, which is
supporting its own considerable weight for hundreds of years, stretching
out towards the ground, and necessarily getting thinker at the bottom.
But there _are_ very important points that differentiate the creep of a
sheet of glass from the creep of a sheet of copper, that lend credence to
the "supercooled liquid" way of thinking.
First of all, the mechanisms are different. (people who got better grades
than me in MatSci, please step in) Metal creeps because it is composed of
crystalline grains, which (by random statistical motion of the atoms) are
always growing and shifting, and which will tend to grow in the direction
of the forces on them. Glass is amorphous, and so its deformation, on a
molecular level, would more closely resemble liquid flow.
Second is the relationship of creep rate to load. A metal would behave
like this (use monospace font):
high |
creep | metal /
rate | /
| __-~
low | _____-------~~~~~
creep | _-~
rate | /
|/_______________________________
light heavy
load load
and glass looks more like the following; that is to say, LINEAR.
high |
creep |
rate | __--~~
| __--~~
low | __--~~
creep | __--~~
rate |__--~~
|________________________________
light heavy
load load
So with glass, double the load would be double the creep rate. With
metals it's mre complicated. The problem is, with liquids (say, molasses
or water or molten glass) the "creep rate" is also linear with the load
... it's called viscosity. In fact, glass deformation is also measured in
terms of viscosity. So in this way glass is indeed liquid-like.
Then we have the question of what happens to glass when you heat it. With
metals and ceramics and crystalline materials, typically it'll be solid
below the melting point and liquid above. (Yeah, like, by definition and
stuff. Heh heh.)
Glass, on the other hand, will get steadily softer and softer. From a
technical standpoint, the viscosity goes down. Hot glass has a low
viscosity and looks like a liquid, cold glass has a high viscosity and
look like a solid. Now, if we're arguing "glass is a solid", then we must
ask is glass a solid at 100 degrees? At 500 degrees? At 2000 degrees?
etc.
Well, since we all agree that molten glass is liquid, we have to pick a
point at which we're going to start calling it solid. This is somewhat
arbitrary, but according to Doremus's _Glass Science_ (1973, quoted
several times on www.urbanlegends.com) "a solid can be defined as a
material with a viscosity of more than about 10^15 P (poises)." That
makes glass, at room temperature, a certified solid. Woo hoo!
I'm happy with that. However, you might note that 10^15 P is just an
arbitrary distinction between solids and liquids. If you don't like it,
you can think of glass as just a "really really viscous liquid", just like
you can think of molasses as a really really weak solid. But it's sort of
pointless, wouldn't you agree? Glass is, for all practical and
theoretical purposes, an amorphous solid. It does NOT flow or deform
measurably under its own weight at room temperature, even over the
timescale of civilizations. (I'll reference you to www.urbanlegends.com,
where various chemical engineers who have actually done the math are cited
saying this.)
So, to summarize, glass, like other amorphous solids, shares many
deformation characteristics with liquids. However, its viscosity is so
high that it does not experience any liquid flow at room temperature. So
the glass window-panes in colonial houses will not be thicker at the
bottom, any more so than the brick walls.
Hope this helps at all.
-Ben
Benjamin Monreal == bmon...@pantheon.yale.edu
==== http://pantheon.yale.edu/~bmonreal ====
==== YPMB YRC CA YMJ Physics TD Yale 99 ====
Carl Fink
In article <Pine.GSO.3.94.970615...@minerva.cis.yale.edu>,
Ben Monreal <bmon...@pantheon.yale.edu> wrote:
>I'm happy with that. However, you might note that 10^15 P is just an
>arbitrary distinction between solids and liquids. If you don't like it,
>you can think of glass as just a "really really viscous liquid" . . .
Yes, but there's a qualitative difference between glass and say,
water.
If you bend a piece of glass and let go, it springs back. As you say
in a part of your message I deleted, elastic deformation. I don't
think water or ketchup show elastic deformation.
There are glass *springs* in some instruments.
--
Carl Fink ca...@dm.net
Manager, Dueling Modems Computer Forum
<http://dm.net>
Lee Rudolph
ca...@panix.com (Carl Fink) writes:
>If you bend a piece of glass and let go, it springs back. As you say
>in a part of your message I deleted, elastic deformation. I don't
>think water or ketchup show elastic deformation.
>
>There are glass *springs* in some instruments.
Why, heck, there are water springs too! I've seen'em myself.
Lee "Where the bluebird sings, and the ketchup springs,
in the Big Mac French-Fry Mountains" Rudolph
Ben Monreal
On Sun, 15 Jun 1997, Carl Fink wrote:
> If you bend a piece of glass and let go, it springs back. As you say
> in a part of your message I deleted, elastic deformation. I don't
> think water or ketchup show elastic deformation.
Yes they do. I have a blob of mayonnaise in front of me as I write ...
I'm poking it ... If I poke it gently, it bends and springs back. Looks
like elastic deformation. It's just a (really huge) quantitative
difference.
Note this does _not_ mean that my windowpanes are thicker at the bottom.
-Ben "I'll ask my grandmother about hers" Monreal
Steve Tyler
Jim Everman wrote:
[SNIP]
>
> Does Mayonnaise Flow?
>
> I contend that it doesn't. It seems to me that the "knife tracks"
> from
> the last time I used the mayonnaise are always still in the jar the
> next
> time I want to use some. Does anyone know the viscosity of mayonnaise?
> Does anyone have a jar of 18th century mayo out there somewhere?
>
> --
> Jim Everman eve...@Anet-STL.com
>
> Never attribute to malice what can be adequately explained by
> stupidity.
Steve Writes:
I thought I would join this thread *again*. since it has now taken a
comic slant.
Mayonnaise exhibits thixotropic behavior. The easy definition is, when
it is stirred, the viscosity goes down, when you stop stirring, the
viscosity goes up. The higher the viscosity, the harder to stir, pour,
etc. Ketchup is the same way. Interestingly, after four years of
ceramic engineering school, I still couldn't figure out how to get
ketchup to pour. A friend who was an English major took the bottle at
dinner one day, he shook in a horizontal circular motion activiating the
thixotrpic behavior and poured. The ketchup came right out. He didn't
even know what thixotrpoic meant.
Thanks,
Steve
Keith M Ellis
In alt.folklore.science Helge Moulding <h...@slc.unisys.com> wrote:
> Joe Deinet wrote:
> > In my original posting some time ago I stated that glass was a liquid,
> I do not care about your semantics. You specifically wrote that "It
> has been shown that cathedral windows which are centuries old are
> always slightly thicker at their base than at their upper end (only
> a very small fraction of a milimeter)."
Isn't this the way it always works with these guys? They
A) Write that "glass is a liquid and it flows in old windows", then
B) When challenged about this, they harp on the "liquid" definition, and
C) Eventually get ridiculously snooty about how "scientists know that
glass is a liquid", but
D) Never back up the claim that it flows in old windows, because
E) They have realized they may be wrong about this, and so retreat to
flame wars about "liquids" and "solids."
The arrogance really gets under my skin, because it is never deserved, and
they are arguably wrong about even the definition of liquid and solid[1].
I still find this psychodrama marginaly interesting, but less so as I can
identify the pathology with more certainty. This guy clearly put his ego
on the line - there's not gonna be any rational discourse with him. All
the references and citations in the world won't make a bit of difference,
since he would lose face to admit he is wrong. Instead, he - like so many
others - will be insulting for awhile, oblivious to citation and
argument, and will eventualy quietly slink away.
It takes a big man to admit when he's wrong[2]. Most people are
itty-bitty, teeny-weeny little creatures.
-Keith Ellis
[1] For the fans on the sidelines: The definitions of "liquid" varies
from discipline to discipline, depending upon what is useful for that
discipline's purposes. For physicists, glass is a liquid, as are many
other things. For a materials scientist, glass is *not* a liquid, since
they are concerned with the physical properties of materials in more
detail - specificaly things like resistance to sheer stress, whether it
flows, etc. Anyone that stands on a blanket claim like "scientists know
that glass is a liquid" knows only enough about science to be dangerous.
[2] I've noticed that, in general, women don't seem to have this problem
as badly.
Mg.
Keith M Ellis <kme...@io.com> wrote:
>In alt.folklore.science Helge Moulding <h...@slc.unisys.com> wrote:
>> Joe Deinet wrote:
>> > In my original posting some time ago I stated that glass was a liquid,
>> I do not care about your semantics. You specifically wrote that "It
>> has been shown that cathedral windows which are centuries old are
>> always slightly thicker at their base than at their upper end (only
>> a very small fraction of a milimeter)."
>The arrogance really gets under my skin, because it is never deserved, and
>they are arguably wrong about even the definition of liquid and solid[1].
It is also too easy to throw arrogance back at arrogance alas with
stylistic criticism taking the place of meaningful dialogue.
Actually I've also heard about the old windows getting thicker at the
bottom. Definitions can go hang , I don't think the models were
designed to simulate centuries old glass , but it doesn't seem
unreasonable as various substances do have different properties on
different timescales. Physics being what it is , I'm not sure it is
fully understood , and we have to fall back on good old empirical
evidence ( does anyone have a citation ? )
>It takes a big man to admit when he's wrong[2]. Most people are
>itty-bitty, teeny-weeny little creatures.
>-Keith Ellis
M.
>[2] I've noticed that, in general, women don't seem to have this problem
>as badly.
I've noticed women claim various things of this sort ( :-)
( in the best possible taste , men are just as bad )
Don McKenzie
In article <33A595...@worldnet.att.net>, Steve Tyler
<sct...@worldnet.att.net> wrote:
> Jim Everman wrote:
>
> [SNIP]
> >
> > Does Mayonnaise Flow?
> >
> > I contend that it doesn't. It seems to me that the "knife tracks"
> > from
> > the last time I used the mayonnaise are always still in the jar the
> > next
> > time I want to use some. Does anyone know the viscosity of mayonnaise?
> > Does anyone have a jar of 18th century mayo out there somewhere?
> >
> > --
> > Jim Everman eve...@Anet-STL.com
> >
> > Never attribute to malice what can be adequately explained by
> > stupidity.
>
> Steve Writes:
[snip]
> ketchup to pour. A friend who was an English major took the bottle at
> dinner one day, he shook in a horizontal circular motion activiating the
> thixotrpic behavior and poured. The ketchup came right out. He didn't
> even know what thixotrpoic meant.
>
Does anybody?
--
Don McKenzie <mca...@wavenet.com>
Republican environmentalists:
Check out <http://www.rep.org>
Colin Dooley
Peter Ceresole wrote:
>
> In article <5o4jch$i...@lyra.csx.cam.ac.uk>,
> xxxx:mt...@hermes.cam.ac.uk (Mg.) wrote:
>
> >Physics being what it is , I'm not sure it is
> >fully understood , and we have to fall back on good old empirical
> >evidence ( does anyone have a citation ? )
>
> determined experimentally; under normal earth surface conditions and over
> millennial time scales, it *doesn't* flow.
>
I seem to remember a posting from somebody who works on a military
centrifuge (whatever that is) and has been using the same glass
tubes for years. This usage would be equivalent to many thousands
of years under normal gravity. He had measured the tubes and
they were no longer than when he started using them.
Helge Moulding
Mg. wrote:
> Yada yada [lot's of masturbation about "might" and "could."]
Look, buddy, the assertion that it flows is what's being questioned.
"Well, it might," is not an answer, nor is whinging about the
deplorable state of 20th centure science. Post a cite or shut up.
--
Helge "Cripes!" Moulding
mailto:h...@slc.unisys.com Just another guy
http://www.geocities.com/Athens/1401 with a weird name
Ian A. York
In article <5o5o7u$j...@lyra.csx.cam.ac.uk>,
Mg. <xxxx:mt...@hermes.cam.ac.uk> wrote:
>
>dubious. I think it's one that perhaps cannot be definitely resolved
>( little evidence for , little evidence against ).
Just because *you* don't know any evidence against it, doesn't mean that
there is no evidence against it. It would be more accurate to say "no
evidence for, vast amounts of theoretical and experimental evidence
against."
I've posted large numbers of references to peer-reviewed articles,
including experimental observations. Look them up and refute them if you
want to insist that there's "little evidence".
And it isn't "little evidence for," it's "no evidence for it, that isn't
fully accounted for by well-documented and well-known manufacturing
methods." Invoking "flowing glass" to account for irregularities in
windows is like invoking fairy princesses to explain the morning dew.
To claim that this isn't "definitely resolved" is entirely false. It is
defintely resolved. There are just a bunch of people who want to believe
in magic and ignore science, who keep insisting that "there's little
evidence against" and then close their eyes and ignore the
counterevidence.
Ian
Illtud Daniel
> Also 'quite well' is not perfect. I assume you're trying to say that
>the flow should be negligible even taken over vast time scales. I
>don't make any claims , I'm just saying that unless somone has some
>evidence in either direction there isn't a lot to say.
a) What part of:
>The cites were posted here by Ian York on 14/6 in message i.d
><5nusj1$d...@panix.com>
(which you snipped from Peter's reply to you) don't you understand?
b) Or did you go away and read them all and decide that they didn't have a
lot to say?
c) Or did you just take the lazy-arse option?
Illtud "betting on c" Daniel
Triple Quadrophenic
In article <5o5o7u$j...@lyra.csx.cam.ac.uk>, xxxx:mt...@hermes.cam.ac.uk
(Mg.) dusted off the quill, prised open the inkwell and wrote...
>
On the other hand hearsay
>measurements of centuries old glass windows ( which were notoriously
>uneven ) , with significance being attached to minute variations seem
>dubious. I think it's one that perhaps cannot be definitely resolved
>( little evidence for , little evidence against ).
There is NO evidence for glass flow. There are millions of bits of
evidence against - try reading dejanews looking for "roman glass",
"obsidian".
--
Frank J Hollis, Mass Spectroscopy, SmithKline Beecham, Welwyn, UK
Frank_...@sbphrd.com or fj...@tutor.open.ac.uk www.chem.u-net.com
These opinions have not been passed by 3 committes, 7 subcommittees and 5
continuous improvement teams. So they can't be the opinions of my employer
Keith M Ellis
In alt.folklore.science Mg. <xxxx:mt...@hermes.cam.ac.uk> wrote:
> Actually I've also heard about the old windows getting thicker at the
> bottom. Definitions can go hang , I don't think the models were
> designed to simulate centuries old glass , but it doesn't seem
> unreasonable as various substances do have different properties on
> different timescales. Physics being what it is , I'm not sure it is
> fully understood , and we have to fall back on good old empirical
> evidence ( does anyone have a citation ? )
Here is Ian York's excellent compilation of citations, with comments:
----quote from Ian York follows-------
Glass does not flow. If you wish to argue this point, please read and
refute the following references, many of which are written by authentic
materials science experts and published in peer-reviewed journals.
Remember to read this full set of references before you attempt to make
any point, because your argument is almost certainly debunked in one or
another of the references. If you read to the end and still disagree,
please cite published references to support the contention that the entire
field of materials science is out to lunch.
More:
NOT FLOW WHEN IT IS SUBJECTED TO MODERATE FORCES. More quantitatively, a
solid can be defined as a material with a viscosity of more than about
--
Ian York (iay...@panix.com) <http://www.panix.com/~iayork/>
"-but as he was a York, I am rather inclined to suppose him a
very respectable Man." -Jane Austen, The History of England
----quote from Ian York end-------
Harry MF Teasley
Mg. (xxxx:mt...@hermes.cam.ac.uk) wrote:
> Hmm , sounds unlikely ( unless you're talking about measuring some
> VERY old windows ). Also do the what do the stars in *doesn't* mean?
> ( an escape clause ? )
Your second question shows that you're extremely new to Usenet, which
comes as no surprise. (To get it out of the way, asterisks or slashes
around a word should be read as italics.) To respond to your point, we
*are* talking about some really old glass, like Roman glass, and Egyptian
glass. The extrapolation that is most commonly made is that if glass a
couple of centuries old in a cathedral window has flowed visibly, then
Roman glass artifacts and Egyptian glass beads should be puddles by this
time. They aren't. Find yourself a primary source for even one of your
claims (multifallacy CD ROM encyclopedias are not primary sources).
> Also 'quite well' is not perfect. I assume you're trying to say that
> the flow should be negligible even taken over vast time scales. I
> don't make any claims , I'm just saying that unless somone has some
> evidence in either direction there isn't a lot to say.
Would that it were so; unfortunately, folks do find a lot to say on the
subject, things like, "Glass flows and I've seen the windows to prove it,
and my high school science teacher said so, too."
I guess my favorite succinct debunking of this UL is Justin's letter to C.
Austin Angell and Prof. Angell's response,
(at http://www.urbanlegends.com/science/glass.flow/angell_letter.html),
which really should shut up anyone who doesn't bring anything but hearsay
to the conversation. Anyway, look in the glass.flow directory at
urbanlegends.com for more of the same in the way of debunkings. There are
other sources on the Net (cited by Ian York previously) if you don't trust
research cited by urbanlegends.com.
Harry "hope this helps" Teasley
--
"Of course, American tourists only shout so they can be heard over their
clothes." -SC
Visit the AFU archives at www.urbanlegends.com
Charles Wm. Dimmick
Ben Monreal wrote:
> On Sun, 15 Jun 1997, Carl Fink wrote:
> > If you bend a piece of glass and let go, it springs back. As you say
> > in a part of your message I deleted, elastic deformation. I don't
> > think water or ketchup show elastic deformation.
>
> Yes they do. I have a blob of mayonnaise in front of me as I write ...
> I'm poking it ... If I poke it gently, it bends and springs back.
> Looks like elastic deformation. It's just a (really huge)
> quantitative difference.
Another example of a material which is neither a classical liquid
nor a crystalline solid. Gels and thick emulsions have their own sets
of rules. Also drifted off-topic for AFU. Perhaps better covered in
alt.sex.messy.
Charles Wm. "keeping it clean" Dimmick
"...and some rin up hill and down dale, knapping the chucky stanes
to pieces wi' hammers like sae mony road-makers run daft -- They say
it is to see how the warld was made!"
Jim McLean
In <33A595...@worldnet.att.net>, Steve Tyler
<sct...@worldnet.att.net> writes (edited):
> A friend who was an English major took the bottle at
>dinner one day, he shook in a horizontal circular motion activiating the
>thixotrpic behavior and poured. The ketchup came right out. He didn't
>even know what thixotrpoic meant.
I'd tend to believe that any effect of shaking the bottle in a
particular way is due to redistribution of the air pocket and/or
the dried-out or oxidized ketchup at the top of the bottle,
rather than any chemical or mechanical changes in the stuff.
Did the ketchup appear to be thinner after shaking than before?
Jim "Heinz-sight is 20/20" McLean
Charles Wm. Dimmick
Colin Dooley wrote:
> Ronda Bandy wrote:
> > <snip because am not sure who wrote this>
> > > Good point. Two or three glass-flow-debate cycles ago, I brought up
> > > the Obsidian Cliff(s), in Yellowstone National Park, USA. This
> > > geographic feature is made of polygon-shaped columns of obsidian,
> > > some huge number of feet high. (The first time I saw the cliffs,
> > > I was reminded of the basalt columns of the Devil's Causeway in
> > > Scotland.)
> > Tower) I believe this is what is left of the lava from inside a
> > volcano. The volcano itself has weathered away. I could be wrong,
> > but I don't believe hardened lava is glass. Is it? Either way,
> > have never heard of it or glass flowing.
> This is indeed columns of Basalt formed by volcanic activity.
OK, a little clarification is in order, just so we get our terms
straight. Lava is a term which may be used either for rock in a
molten state as it comes out of the ground (volcano or fissure flow),
or for the hardened material after the liquid lava cools. There is
a wide range of chemical compositions for lava, mostly in variations
of the percentage of silica and iron. Liquid lava which is high in
iron and low in silica flows very easily and cools to form a volcanic
rock called basalt. This is the lava of the Giant's causeway and of
all the Hawaiian Islands. Liquid lava which is high in silica and low
in iron is quite viscous, even at high temperature, and almost
incapable of flow, except under pressure. It has roughly the flow
characteristics of taffy. Such lava may cool to form Rhyolite, a
very fine-grained crystalline igneous rock, or if cooling is relatively
rapid it will cool to form Obsidian, also known as volcanic glass.
The Obsidian Cliffs are made of Obsidian, thus they are glass. They
are also lava, since they cooled on the surface from a molten state.
To answer a question from another post which never made it to my
server (I found it by accident on dejanews), all glass will eventually
become non-glass, in other words it will devitrify. In the case of
obsidian, after millions of years all the obsidian will become a
mass of cryptocrystalline aggregates of quartz and feldspar. A sample
of obsidian from the obsidian cliffs, viewed in thin section under
a petrographic microscope will show this change about 10-20%
complete.
Charles Wm. Dimmick
"...and some rin up hill and down dale, knapping the chucky stanes
to pieces wi' hammers like sae mony road-makers run daft -- They say
it is to see how the warld was made!"....Sir Walter Scott
C Lamb
Triple Quadrophenic (Frank_H...@sbphrd.com.see-sig) wrote:
: In article <5o5o7u$j...@lyra.csx.cam.ac.uk>, xxxx:mt...@hermes.cam.ac.uk
: >
: On the other hand hearsay
: >measurements of centuries old glass windows ( which were notoriously
: >uneven ) , with significance being attached to minute variations seem
: >dubious. I think it's one that perhaps cannot be definitely resolved
: >( little evidence for , little evidence against ).
: There is NO evidence for glass flow. There are millions of bits of
: evidence against - try reading dejanews looking for "roman glass",
: "obsidian".
As a rider - I think glass flow would have been noticed by many physicists
over the years because they would have to re-grind optics in interferometers
made before WWII that require accuracy better than 1/20th wave.
just my 2p
Chris
: --
Kelly Miller
tay...@cyllene.uwa.edu.au wrote:
> Ben Monreal wrote:
> >
> > On Sun, 15 Jun 1997, Carl Fink wrote:
> >
> > > If you bend a piece of glass and let go, it springs back. As you say
> > > in a part of your message I deleted, elastic deformation. I don't
> > > think water or ketchup show elastic deformation.
> >
> > Yes they do. I have a blob of mayonnaise in front of me as I write ...
> > I'm poking it ... If I poke it gently, it bends and springs back. Looks
> > like elastic deformation. It's just a (really huge) quantitative
> > difference.
>
> Is this because of surface tension, and not elatic deformation? I
> remember an experiment, how to touch water without getting wet -
> sprinkle white pepper on the surface and it forms a layer that ...
No, mayonaise and ketchup and a slew of other colloids can have small but
measurable elasticities and yield stresses. But while the moduli of
inorganic solids are in the range of ~50-300 GPa (glass has a modulus of
70 GPa), the moduli of colloidal solids in the range Pascals to kPa's.
So mayo is still an elastic solid, only a billion times less stiff than glass.
Kelly Miller
ktmi...@mines.edu
Kelly Miller
In article <5o8rqu$1ksg$1...@rtpnews.raleigh.ibm.com>,
mcl...@bcrvm1.vnet.ibm.com wrote:
Nice pun! Despite that, shear of any sort to a network of attractive
colloidal particles (like ketchup) can temporarily break up the
structure. The particles can now move past one another more easily, and
the stuff becomes thinner. Eventually, the network reforms, and the
material once again becomes thicker.
Movement of air bubbles during shaking might help with the mixing, but
their effect is secondary, at best.
Kelly Miller
ktmi...@mines.edu
Colin Dooley
Kelly Miller wrote:
> Despite that, shear of any sort to a network of attractive
> colloidal particles (like ketchup) can temporarily break up the
> structure. The particles can now move past one another more easily, and
> the stuff becomes thinner. Eventually, the network reforms, and the
> material once again becomes thicker.
>
> Movement of air bubbles during shaking might help with the mixing, but
> their effect is secondary, at best.
>
Does anybody know how to get ketchup out of a *new* bottle.
Half empty bottles are easy, but a new bottle, that's something else!
FTB
PS: I usually buy the skwee-zee bottles myself, this is just out
of interest...
Keeper of the Cheese
>
>Does anybody know how to get ketchup out of a *new* bottle.
>
>Half empty bottles are easy, but a new bottle, that's something else!
>
>
>FTB
>
wiggle the business end left to right a bit. works every time.
Harry Flashman
You are so wrong!
Even with a Masters in biochemistry I know that Glass is a fluid. If you
don't believe me refer to the "Journal of Non-Crystaline Solids". You will
find that it is definately possible to measure the elasticity and
viscosity of various glasses.
Silica glass is made from naturaly occuring silica crystals which are
ordered tetrahedrons of Silicon and Oxygen. During the formation of glass
the cyrstals are melted and loose this structure, higher temperature, more
structure is lost, meaning the cyrstals are no longer ordered tetrahedrons
and they "flow" across each other. During the cooling process, *some* of
the order is restored, but in most cases, depending on the purity of the
silica, the tempertures to which it was exposed, and the rapidity of
cooling, the crystals DO NOT reform. Therefore the results is an
"amorphous" structure, not a polymer, and the glass retains some of the
fluidity, and viscosity properties it had as a melted substance.
It is just that the time frame, and the visual context in which we observe
glass, leads us to beleive it is a "solid" and not a fluid.
Scott
McGinnis
Jim Everman (eve...@anet-stl.com) wrote:
: > > I suggest that anyone doubting this find someone who has
: > >studied physics or advanced physical chemistry at some university and
: > >have this explained.
: >
: > Many of the poeple responding to you have studied these subjects in
: > college.
:
: Well, I have a degree in physics and I think that glass is a liquid
: with a viscosity so damn high that, for all practical purposes, IT
: DON'T F***ING FLOW! OK?
:
: --
:
Helge Moulding
Harry Flashman wrote:
> Even with a Masters in biochemistry I know that Glass is a fluid.
No one cares about your degree, or if you think glass is a fluid.
The point at issue is the claim that the "fact" that glass is a
"fluid" has been demonstrated by observing that the glass in old
windows has "flowed". You are invited to post an actual cite of
such an observation, one that is *more* substantive than the usual
"it has been shown that glass in old windows has flowed".
As a person with a master's degree in biochem you should have the
necessary research skills to find the source, if it exists at all.
--
Helge "High water mark." Moulding
Ian A. York
Posted and mailed.
In article <5ouioh$d...@clarknet.clark.net>,
Harry Flashman <sir...@clark.net> wrote:
>
>Even with a Masters in biochemistry I know that Glass is a fluid. If you
>don't believe me refer to the "Journal of Non-Crystaline Solids". You will
>find that it is definately possible to measure the elasticity and
>viscosity of various glasses.
Someone a little less eager to justify himself (or who wasn't trolling,
perhaps) might have been a trifle puzzled by the title of the journal,
specifically by the prominent role of the word "solid". He might also be a
trifle puzzled by the assignment of *elasticity*, a property of a solid,
to glass.
You apparently haven't actually read much of the journal, because an
article in there shows why you are almost entirely wrong (though you are,
of course, a little bit right).
In theory, and if the world were a simpler place, something to which a
viscosity could be assigned would (eventually) flow. However, this is the
real world, an ugly place filled with trolls and solid effluvia, and in
this world not all substances with an assigned viscosity do flow.
The reason is that it is perfectly possible to assign viscosities which
are so high that the substance won't flow in the lifespan of the universe.
It is also possible to assign viscosities which are high enough that the
substance will not flow before other changes (like crystallization) happen
to it. This is true for glass, including window glass.
>It is just that the time frame, and the visual context in which we observe
>glass, leads us to beleive it is a "solid" and not a fluid.
No, it's the fact that glass does not flow detectably, no matter what the
time frame, that leads us (and experts in glass science) to believe that
glass is a solid and not a fluid.
Before you continue your argument, please read and refute the following
references, including the one in the Journal of Non-Crystalline Solids,
which most clearly demonstrates my point.
Peter Ceresole
In article <5ouioh$d...@clarknet.clark.net>,
sir...@clark.net (Harry Flashman) wrote:
>It is just that the time frame, and the visual context in which we observe
>glass, leads us to beleive it is a "solid" and not a fluid.
Well, I'd say that if it doesn't flow over a time scale of several thousand
years at standard temperatures, we may as well call it a solid, don't you
think?
Of course there are all those shop windows that flow out of their frames
onto the pavement in the hot weather, but let's not talk about them.
Somebody posted the FAQ, which is a large list of cites, not many weeks
ago, because this one does come up so often...
From an engineering and a human viewpoint, glass is a solid. By the time it
might demonstrate flow it has crystallized, so it's still a solid.
It's a solid.
--
Peter
JoAnne Schmitz
On 26 Jun 1997 20:17:21 GMT, sir...@clark.net (Harry Flashman) wrote:
>Even with a Masters in biochemistry I know that Glass is a fluid.
Isn't a Masters degree in many academic disciplines something like a
consolation prize? I know I've heard that about Johns Hopkins
degrees.
JoAnne "shooting a cannon down the hallowed halls of academe" Schmitz
Chris Grace
Harry Flashman (sir...@clark.net) wrote:
: You are so wrong!
: Even with a Masters in biochemistry I know that Glass is a fluid. If you
[...]
: the cyrstals are melted and loose this structure, higher temperature, more
^^^^[1]^ ^^[2]^
[1] Is this a new kind of object only known to Master Biochemists? You've
used the word more than once. What is it?
[2] Is this like letting the structure out of a horse box? Or is it a
Master Biochemist's version of the 3rd person plural of the verb 'to Lose'?
When I studied biochemistry it required a certain element of precision in
expression. Either biochemistry has sadly dropped its standards,
particularly for Masters candidates, or your claims to qualifications are
wrong.
Your intellectual achievements are of little interest in any event when
you insist on discussing a subject which a cursory reading of both
newsgroups to which you have posted would tend to indicate that
1.WE DON'T GIVE A FUCK ABOUT YOUR OR ANYONE ELSE'S OPINION ABOUT THE
PROPERTIES OF GLASS
2. People who prefix their meanderings about their academic qualifications
are usually assumed to be self-important prigs.
Piss off.
--
Chris 'fufas' Grace Somewhere south of the equator and north of antarctica
Gil Myers
Dr. Peter Kittel <pet...@combo.ganesha.com> wrote in article
> from there found in regions of the Czech republic), and is unchanged
since
> then. (There is a more specific name for these pellets, but I don't
> remember it, sorry.)
tektites?
Doug the Desert Tripper
On Sat, 14 Jun 1997 18:09:37 GMT, jde...@shentel.net (Joe Deinet)
wrote:
>
>
>In my original posting some time ago I stated that glass was a liquid,
>but that it could not be observed to flow in a short period of time.
The thing that puts this issue to rest for me is some of the vacuum
(radio) tubes I have in my collection. A few of these tubes are over
60 years old, yet the glass envelopes are perfect. If glass were a
"fluid" as is postulated, the vacuum (and hence the pressure of
atmospheric air outside the envelope) acting continuously over so many
years would have begun to cause the thin glass to fold inward.
--------------------------------------------------------------------------------------
Doug the Desert Tripper - Exploring Southern Cal deserts and the Net since '94
E-Mail: des...@linkline.com - Serious Inquiries only; Spammers need not apply.
--------------------------------------------------------------------------------------
Hairy One Kenobi
>From an engineering and a human viewpoint, glass is a solid. By the time it
>might demonstrate flow it has crystallized, so it's still a solid.
>
>It's a solid.
Actually, we were taught in our materials class that it is technically
a supercooled liquid, but can be treated as a solid for all practical
purposes.
From personal experience, I can cite a cottage in Wiltshire, where
*all* of the windows bar one were thicker at the bottom than at the
top. Popular conception means that it has flowed. This is not
necessarily the case: unless an observer was there to check that this
was not the case a couple of years after installation, it has not
flowed over time. There was enough discolouration at the bottom of the
galss to suggest a high level of impurities; these could have allowed
the glass to flow (unlikely at best) or indicate that the pane was
stood-up vertically on a dirty floor, and was still molten enough to
absorb impurities from the floor through diffusion. If it's _that_
molten, then it's soft enough to flow.
Put it down to the state of glass manufacturing processes circa 1600.
Note: the opinions expressed in this opinion do not necessarily
represent the opinions of the opinionated person expressing the
opinion. Or something.
Jimmy Vaughn
Jim McLean wrote:
> In <33A595...@worldnet.att.net>, Steve Tyler
> <sct...@worldnet.att.net> writes (edited):
>
> > A friend who was an English major took the bottle at
> >dinner one day, he shook in a horizontal circular motion activiating
> the
> >thixotrpic behavior and poured. The ketchup came right out. He
> didn't
> >even know what thixotrpoic meant.
>
> I'd tend to believe that any effect of shaking the bottle in a
> particular way is due to redistribution of the air pocket and/or
> the dried-out or oxidized ketchup at the top of the bottle,
> rather than any chemical or mechanical changes in the stuff.
> Did the ketchup appear to be thinner after shaking than before?
>
> Jim "Heinz-sight is 20/20" McLean
Ketchup is a good example of a shear-thinning viscoelastic fluid.
Under stress, it actually gets thinner, and returns to its normal
viscosity if allowed to sit still. That's why shaking a bottle of
ketchup vigorously allows it to pour more easily. Just the opposite (a
shear-thickening viscoelastic fluid) is the stuff now called Gakk. If
you pull it gently, it flows like putty. If you give it a sudden jerk,
it stiffens and parts on a plane.
Scientific American had a great article on this subject around (gulp!)
twenty years ago.
col...@cs.umn.edu
Glass is solid in the sense that it does not flow the way water does
but it is not a solid in another sense. It is what is called in
chemistry a supercooled liquid. It does not, for example, form a
crystalline structure.
Freshly cut glass is sharper than that same glass will be after it has
aged for some time. You or I may not notice the difference but the
glass does flow, albeit slowly.
As to the vacuum tubes, they cannot be made of the same glass that,
for example, windows or soda bottles are made of. If you made vacuum
tubes of high iron content window glass, they very likely would
exhibit the "behavior" you describe as proof that glass is not liquid.
Jim - col...@cs.umn.edu
Ian A. York
In article <5p6qoe$4...@epx.cis.umn.edu>, <col...@cs.umn.edu> wrote:
>
>Freshly cut glass is sharper than that same glass will be after it has
>aged for some time. You or I may not notice the difference but the
And your cite for this, from a peer-reviewed journal (as opposed to
Science Phun Phacts Phor Kiddies) is .... ?
>As to the vacuum tubes, they cannot be made of the same glass that,
>for example, windows or soda bottles are made of. If you made vacuum
"Cannot" because that would contradict your unsupported belief? Of
"cannot" because you actually have some evidence for this?
Note that the viscosity of window glass (between 10^19 and 10^28 poise,
depending on the exact composition) is over one million times greater than
the level that's used as a cutoff between solids and liquids (i.e. 10^13
poise). The most common viscosity given is around 10^22: one hundred
million times greater. Do you believe that the people who work with glass
are so incompetent as to be off by one hundred million-fold?
You "evidence" for believing that glass flows one hundred million times
faster than the experts believe is easily interpreted as manufacturing
defects. Considering what is well known, and well documented, about glass
manufacturing techniques, it's infinitely easier to believe that this is
the source of the defects. Unless, of course, you prefer to believe in
undocumented anecdotes and tour guides' claims.
Ian
Hairy One Kenobi
On Mon, 30 Jun 1997 08:07:17 -0600, Helge Moulding
<h...@slc.unisys.com> wrote:
>Remember, I do not care if you want to call glass a liquid - I
>disagree, but for the purposes of this discussion that is totally
>besides the point. The question is, can you support the claim "it
>has been shown that glass in old windows flows" with a real cite,
>where someone has made a scientific investigation of the claim, and
>proven it to be true?
The problem is that you will never get a believable citation: noone
documents a house as having windows that _aren't_ thicker at the
bottom than at the top, Without that, you'd have to resort of
photography. Even the proponents do not beleive of flow over such a
short period of time.
On the other hand, I *do* agree with the stipulation tha glass is a
supercooled liquid.
Donald DiPaula
In article <33b7fdb6....@news.demon.co.uk>,
Hairy One Kenobi <ha...@advsystems.demon.co.uk> wrote:
!On Mon, 30 Jun 1997 08:07:17 -0600, Helge Moulding
!<h...@slc.unisys.com> wrote:
!>Remember, I do not care if you want to call glass a liquid - I
!>disagree, but for the purposes of this discussion that is totally
!>besides the point. The question is, can you support the claim "it
!>has been shown that glass in old windows flows" with a real cite,
!>where someone has made a scientific investigation of the claim, and
!>proven it to be true?
!
!The problem is that you will never get a believable citation: noone
!documents a house as having windows that _aren't_ thicker at the
!bottom than at the top, Without that, you'd have to resort of
!photography. Even the proponents do not beleive of flow over such a
!short period of time.
actually, all you need to document is that the glass was of uniform thickness
when installed and could not have been thicker at any end due to an imperfect
glass creation process.
!On the other hand, I *do* agree with the stipulation tha glass is a
!supercooled liquid.
no comment.
Donald "pyr*m*ds fl*w!" DiPaula
--
By US Code Title 47, Sec.227(a)(2)(B), a computer/modem/printer meet the
definition of a telephone fax machine. By Sec.227(b)(1)(C), it is unlawful to
send any unsolicited advertisement to such equipment, punishable by action to
recover actual monetary loss, or $500, whichever is greater, for each violation.
Harry H Conover
Helge Moulding (h...@slc.unisys.com) wrote:
: Hairy One Kenobi wrote:
: > On Mon, 30 Jun 1997 08:07:17 -0600, Helge Moulding
: > >can you support the claim "it has been shown that glass in old
:
: Fine, then why is it that "glass in old windows flows" is trotted
: out as "proof" that glass is a liquid? If there are no cites for
: that, then people shouldn't bring it up, don't you agree?
In passing, let me offer the comment that this subject has been
discussed repeatedly and ad nausium in sci.physics. There, it's
pointed out that old glass is thicker at the bottom simply because
the manufacturing processes of the time could not easily produce
inexpensive, uniform thickness panes. Evidently, the installation
conventions of that era prescribed mounting the uneven thickness
panes with the thick edge at the bottom.
I don't recall that group ever reaching a consensus re. glass being
a liquid or a solid, primarily because some of the experts in the
field continue on with endless dialog that focuses on very
esoteric scientific arguments and subtle differences in technical
semantics. However, it did come out that if glass actually flows
at less than elevated temperatures, results of that flow would
not easily be measurable in glass panes produced only a few
hundred years in the past. (I believe someone there actually
ran some caclulations of this.)
Harry C.
Helge Moulding
Hairy One Kenobi wrote:
> On Mon, 30 Jun 1997 08:07:17 -0600, Helge Moulding
> >can you support the claim "it has been shown that glass in old
> >windows flows" with a real cite
> The problem is that you will never get a believable citation:
Fine, then why is it that "glass in old windows flows" is trotted
out as "proof" that glass is a liquid? If there are no cites for
that, then people shouldn't bring it up, don't you agree?
> Even the proponents do not beleive of flow over such a short
> period of time.
Waitaminnit! What a blatant lie! Proponents post precisely this
claim time and again. It's usually their cue de glass to silence
anyone who says glass is a solid. "Why is it that it shows flow
in old windows?" they ask, chuckling evilly to themselves. I've
got him that time, they think. And it is that claim which makes
this whole discussion on topic for AFU. Otherwise, take it to
sci.masturbations, where endless arguments about terminology are
deemed entertaining.
--
Helge "Stumped?" Moulding
Ben Clifford
In alt.folklore.urban col...@cs.umn.edu wrote:
: Freshly cut glass is sharper than that same glass will be after it has
: aged for some time. You or I may not notice the difference but the
: glass does flow, albeit slowly.
A freshly purchased Swiss Army penknife is shaper than that same
Swiss Army penknife will be after it has aged for some time. Swiss
Army penknives do flow, albeit slowly.
--
PGP 0xD4C9C0B1
macb3th
In article <33B6F25A...@earthlink.net>, Jimmy Vaughn
> Ketchup is a good example of a shear-thinning viscoelastic fluid.
> Under stress, it actually gets thinner, and returns to its normal
> viscosity if allowed to sit still. That's why shaking a bottle of
> ketchup vigorously allows it to pour more easily. Just the opposite (a
> shear-thickening viscoelastic fluid) is the stuff now called Gakk. If
> you pull it gently, it flows like putty. If you give it a sudden jerk,
> it stiffens and parts on a plane.
>
> Scientific American had a great article on this subject around (gulp!)
> twenty years ago.
I remember a physics nerd friend of mine showing me a similar trick.
Apparently he had just come back from a physics conference where he
learned, among other things, about antiprotons and how to blow the bottom
off a beer-bottle with your hand. Anyways, he went to lunch, and being
nerds, they proceeded to debate how to best extract the offending liquid
from the bottle. One guys suggested something similar to the explanation
above, while another just did the "scoop it out with a knife trick".
However, one of them really had an idea...
He grabbed the ketchup bottle with his right hand, turned it about 45
degrees, and aimed it at the plate. He then held out his hand about 3
inches in front of his other hand (which was holding the bottle), and
proceeded to slam the bottle into that hand. Well, let's just say it
worked. He emptied half the damn bottle onto the plate, and proceeded to
explain about momentum (drawing on napkins of course), while everyone else
tried to clean the stuff out of their shirts.
I've seen this done, it's quite impressive.
Jason "good things come to those who rapidly decelerate" Leane
010101010101010101010101010101010101010101010101010101010101010
Macb3th "Math is to physics as masturbation
jle...@netcom.ca is to sex." -- Richard Feynman
010101010101010101010101010101010101010101010101010101010101010
Helge Moulding
Harry H Conover wrote:
> Helge Moulding (h...@slc.unisys.com) wrote:
> : Fine, then why is it that "glass in old windows flows" is trotted
> : out as "proof" that glass is a liquid? If there are no cites for
> : that, then people shouldn't bring it up, don't you agree?
> because the manufacturing processes of the time could not easily
> produce inexpensive, uniform thickness panes.
The problem with this is that no one has actually produced the
evidence that old glass *is* thicker at the bottom. You see, that
is the science myth, and that is what I'm challenging anyone who
wants to bring up the subject to show: that there is, somewhere,
actual research into the relative thicknesses of top and bottom
edges of elderly glasspanes.
--
Helge "If you can't show, it doesn't flow." Moulding
Simon Slavin
In article <5p6qoe$4...@epx.cis.umn.edu>,
col...@cs.umn.edu wrote:
> Freshly cut glass is sharper than that same glass will be after it has
> aged for some time. You or I may not notice the difference but the
> glass does flow, albeit slowly.
Are you suggesting that the 'blunting' of freshly cut glass
over time is related to the flowing of glass ? Isn't it
likely that stress and strain cause the (now extremely thin)
glass to fracture until there are few extremely thin parts
left ? This could happen at the edges of each piece until
the edges were blunt.
> As to the vacuum tubes, they cannot be made of the same glass that,
> for example, windows or soda bottles are made of. If you made vacuum
> tubes of high iron content window glass, they very likely would
> exhibit the "behavior" you describe as proof that glass is not liquid.
The original point, as described in the AFU FAQ, discusses
standard glass (window-glass) at STP. If you have proof of
any type of glass that flows when cooler than, say, 100C
below its glass transition temperature, we'd be interested
in hearing it.
Simon.
--
Simon Slavin -- Computer Contractor. | [AFU has] been nothing but a high-
http://www.hearsay.demon.co.uk | tech lynching since I've been here.
Check email address for spam-guard. | Well, I'm moving on. -- Nat Turner
Junk email not welcome at this site. | <tur...@smarty.smart.net.NOJUNK>
Hairy One Kenobi
On Mon, 30 Jun 1997 16:38:47 -0600, Helge Moulding
<h...@slc.unisys.com> wrote:
>> The problem is that you will never get a believable citation:
>
>out as "proof" that glass is a liquid? If there are no cites for
>that, then people shouldn't bring it up, don't you agree?
I didn't. I was replying to someone else's post.
>
>> Even the proponents do not beleive of flow over such a short
>> period of time.
>
>Waitaminnit! What a blatant lie! Proponents post precisely this
>claim time and again. It's usually their cue de glass to silence
>anyone who says glass is a solid. "Why is it that it shows flow
>in old windows?" they ask, chuckling evilly to themselves. I've
Define "short time". I am using it in reply to the original poster
(years, not centuries). Let's not get white-knuckled at the keyboard,
here.
Hairy One Kenobi
On Tue, 01 Jul 1997 09:35:14 -0600, Helge Moulding
<h...@slc.unisys.com> wrote:
>The problem with this is that no one has actually produced the
>evidence that old glass *is* thicker at the bottom. You see, that
>is the science myth, and that is what I'm challenging anyone who
>wants to bring up the subject to show: that there is, somewhere,
>actual research into the relative thicknesses of top and bottom
>edges of elderly glasspanes.
Read my citation above. But, before replying, please note my suggested
reason.
Hairy One Kenobi
On 30 Jun 1997 15:42:03 -0400, dip...@access5.digex.net (Donald
DiPaula) wrote:
>actually, all you need to document is that the glass was of uniform thickness
>when installed and could not have been thicker at any end due to an imperfect
>glass creation process.
Does you new double glazing state that in a certificate? Does anyones?
Will they ever? Want to be the first?
Peter Ceresole
In article <33BA67...@slc.unisys.com>,
Helge Moulding <h...@slc.unisys.com> wrote:
>Where does this science myth come from? Did it spontaneously generate
>in many places or is there a single source for this claim?
I think it's just good story. That's all it takes to make a UL. It doesn't
have to be even remotely true. Look at how many idiots appear to believe
the X-Files are true...
You mean they're not...?
--
Peter
Helge Moulding
Hairy One Kenobi wrote:
> Read my citation above. But, before replying, please note my suggested
> reason.
I suppose you mean what you posted on June 26:
> From personal experience, I can cite a cottage in Wiltshire, where
> *all* of the windows bar one were thicker at the bottom than at the
> top.
You point out yourself that that is not a cite. Dozens of people
have posted items like yours. No one has posted the sort of cite
that could be used to support "it has been shown that glass in old
windows flows." That is what I'm waiting to see, and, as far as the
alt.folklore.urban and the alt.folklore.science newsgroups are
concerned, the thing that makes this discussion of interest to these
newsgroups: the claim is made in many places, but never has any
actual support. When the people who might be making these claims are
asked where they got that from, the answer is generally something
along the lines of "I thought everyone knew that," or "I read it
somewhere." True answers, but useless nevertheless.
(I witnessed one particularly fun exchange when I wrote the author
of one of these claims, a historian, who forwarded my question to
a glass chemist. The historian's reply was, of course it flows. No
cite, of course. The glass chemist wrote, both to me and the
historian, nonsense, there's nothing to that claim.
Well, I found it amusing.)
Where does this science myth come from? Did it spontaneously generate
in many places or is there a single source for this claim?
--
Helge "Startling clarity" Moulding
Bill Bradley
In article <33B923...@slc.unisys.com>,
Helge Moulding <h...@slc.unisys.com> wrote:
>Harry H Conover wrote:
>> Helge Moulding (h...@slc.unisys.com) wrote:
>> : out as "proof" that glass is a liquid? If there are no cites for
>> : that, then people shouldn't bring it up, don't you agree?
>> because the manufacturing processes of the time could not easily
>> produce inexpensive, uniform thickness panes.
>
>evidence that old glass *is* thicker at the bottom. You see, that
>is the science myth, and that is what I'm challenging anyone who
>wants to bring up the subject to show: that there is, somewhere,
>actual research into the relative thicknesses of top and bottom
>edges of elderly glasspanes.
The observation that the glass is thicker on the bottom is probably
what started the myth of glass flowing.
When glass planes were spun (as opposed to modern "float" glass) then
cut, they had a thicker end. This was put on the bottom for stability. So
many older buildings do have glass panes that are thicker on the bottom...and
always have been.
Bill
Helge Moulding
Bill Bradley wrote:
> The observation that the glass is thicker on the bottom is probably
> what started the myth of glass flowing.
Maybe. What I'm getting at is that as an observation it isn't
specifically documented *anywhere*. Even your own reasonable
sounding suppositions aren't grounded in anything other than
fancy. There is no evidence that, should I survey all old
installations of window glass, I would find a preponderance of
panes with the thick edge at the bottom.
There is not, for that matter, any reason to say that there was
a general practice of placing glass panes with the thicker edge
downwards, to explain the *supposition* that the majority of panes
have the thicker edge down. No one has found a glazer's manual that
says anything of the kind. I might amplify that another explanation
could be that the thicker parts would also be more opaque - glass
graying agents being what they are - and the darker portion might
be considered less noticable if placed at the bottom edge of a
window, instead of the top edge.
As it is, no one has been able to find an article anywhere on "the
observation of old window glass that's fat at the lower edge." The
most we get is individuals posting their personal observations,
which mostly consist of "I looked at it, and it appeared thicker."
Not so much as a go with calipers. Even a fellow whose job consists
of taking windows apart had to concede that you can't "usually"
notice any thickening at all. Even though he believed that window
glass flows.
When we do find cites, they seem to say the exact opposite. See
Ian's list, which includes an item by a restorer of stained glass
windows, who says he's found the bits' fat edges pointing up, down,
or sideways.
And yet there are about a dozen books on my list by now that say
something along the lines of "it has been shown that old window
glass flows." If people want to say "it has been shown," then
where's the cite?
--
Helge "Where's the cite?" Moulding
Illtud Daniel
Helge Moulding <h...@slc.unisys.com> wrote:
>Where does this science myth come from? Did it spontaneously generate
>in many places or is there a single source for this claim?
Personally, I believed gl*ss fl*w to be real until I saw it being hashed
out here. I have no recollection at all of being taught it, and believe
that my belief was a spontaneous (and let's face it, plausible*) reaction
to seeing 'wavy' 'drippy' glass, and possibly the transparent=liquid/ice
connection as well.
[* in an ignorant way]
--
Illtud Daniel ida...@jesus.ox.ac.uk
-Read Mr Nice (now available in paperback!)- -Buy Apollo 440-
"Granny didn't have any real chips, so she had to make em out of potatoes."
Little kid, Cardiff.
Ian Munro
Illtud Daniel (ida...@jesus.ox.ac.uk) wrote:
: Helge Moulding <h...@slc.unisys.com> wrote:
: >Where does this science myth come from? Did it spontaneously generate
: >in many places or is there a single source for this claim?
: Personally, I believed gl*ss fl*w to be real until I saw it being hashed
: out here.
Maybe I'm going crazy, but didn't this only become an "F" about 3-4 years
ago? I'd swear that when I first started reading the group afu was on the
side of the flowbies. Any of the elder afuisti remember this, or have I
strayed even further into lunacy? (On a side note: I also seem to
remember the old faqs being kept in the archive, but I can't find them
there now.)
Ian "where have all the Good Times gone?" Munro
--
"It may or may not be true (I would guess not) but I'm pretty sure I've
heard this one before, although I can't remember where."--Andrew Goldstein
Robert Gotschall
In article <5pj496$3...@news.ox.ac.uk>, ida...@jesus.ox.ac.uk says...
> Helge Moulding <h...@slc.unisys.com> wrote:
>
> >Where does this science myth come from? Did it spontaneously generate
> >in many places or is there a single source for this claim?
>
> Personally, I believed gl*ss fl*w to be real until I saw it being hashed
> that my belief was a spontaneous (and let's face it, plausible*) reaction
> to seeing 'wavy' 'drippy' glass, and possibly the transparent=liquid/ice
> connection as well.
>
flow by my high school physics teacher. However, I recall nothing about
it doing so on a human time scale, and certainly no one suggested looking
at window panes. Perhaps just a case of -a little knowledge-.
hob
Lee Rudolph
sen...@ugcs.caltech.edu (Bill Bradley) misses Helge's point completely:
>In article <33B923...@slc.unisys.com>,
>Helge Moulding <h...@slc.unisys.com> wrote:
>>
>>The problem with this is that no one has actually produced the
>>evidence that old glass *is* thicker at the bottom. You see, that
>>is the science myth, and that is what I'm challenging anyone who
>>wants to bring up the subject to show: that there is, somewhere,
>>actual research into the relative thicknesses of top and bottom
>>edges of elderly glasspanes.
>
> The observation that the glass is thicker on the bottom is probably
>what started the myth of glass flowing.
Let me say it again, slowly. When you say "The observation", you are
begging the question. Helge's point is that *there has been no such
observation*: more precisely, that no one has ever given us ANY evidence
that glass in some broad--or even narrow--range of windows has been
examined and shown to be "thicker on the bottom" with any degree of
uniformity.
You got such an observation (like, written down and published, and
all), you're gold.
Lee "otherwise, you're a plumb bum" Rudolph
Hairy One Kenobi
On 6 Jul 1997 18:25:23 -0400, lrud...@panix.com (Lee Rudolph) wrote:
>Let me say it again, slowly. When you say "The observation", you are
>begging the question. Helge's point is that *there has been no such
>observation*: more precisely, that no one has ever given us ANY evidence
>that glass in some broad--or even narrow--range of windows has been
>examined and shown to be "thicker on the bottom" with any degree of
>uniformity.
I can (as stated earlier) a definite cite of a cottage with noticable
and measurable thickening at the bottom of the glass. I'll have to do
some digging as to an actual address: it is in Devises in Wiltshire,
UK, near the churchyard. It is around 1.5-2 time s thicker at the
bottom than at the top. Total glass area (per window) is around twelve
inches on a side.
As I have also stated, I believe the difference more likely due to
manufacturing tolerances.
Matt Giwer
Helge Moulding <h...@slc.unisys.com> wrote:
>Where does this science myth come from? Did it spontaneously generate
>in many places or is there a single source for this claim?
One suggestion as to the origin is that old glass making
techniques did not produce parallel sides but had a thicker edge which
glazer put on the bottom. A hundred years later when the only thing
everyone has seen is parallel glass, it is an obvious explanation.
Since it does not flow and there is a thicker edge the answer
would appear to be in the manufacturing process.
=====
If what Pat Buchanan says sounds better in the original German then ...
Ivan Boeski. "Greed is good." But it sounds better in the original Yiddish.