The article lists a cordon steel. I believe that would be Cor-ten.
John B
Sent: Sat, Aug 7, 2010 11:44 am
See http://is.gd/e7Kyq for a newspaper article about next week's NASS
conference.
Fred Sawyer
=
---
I should add that the sudden change where the tube comes up out of the
concrete will cause a stress concentration. The factor can be up to 3 times.
One way to handle the problem is with a compliant mount, but that will lead to
the gnomon moving to unforeseen positions. Better, I think,
Hi John C,
Not to worry, politicos are often frightened by such things. Comes from lack
of practical experience or from innumeracy, though of course, you will often
find both in the same politician. That's why many people treat them like
mushrooms. C'est la vie.
We should look at the
John C,
OK, just got back from meetings. Five minutes gives me the attached. I bumped
the wall thickness to 1/8 as suggested. Good plan.
It would be an air roar to say the 12' cantilever is stiffer or stronger than
the 24' gnomon rigidly supported at both ends. However, a perfectly
All of the scary equations were hidden in the spreadsheet I sent out.
Hidden so as not to scare anyone. Did the spreadsheet arrive unreadable?
Unfathomable?
John B
-Original Message-
From: Roger Bailey [EMAIL PROTECTED]
To: John Carmichael [EMAIL PROTECTED]; 'Sundial
Most tubes aren't perfectly straight, so it behooves one to rotate the tube
until the high point is up.
I agree that axial compliance is needed. However, sockets tend to be a little
loose, and so you might lose your rigid support status. (Rigid supports cause
three bends in a bar while
Oh, I concur wholeheartedly. If it's an end attachment it's one thing, but if
you want to fill the tube with it so as to make the tube stiffer, there are
actually better ways. I also agree with the guy who said don't make your wall
too thin. If it's too thin, it's not dent resistant. A
Maybe everyone understands a double elastic hinge, but in case there is one
person who doesn't, sketch attached. Thinner plates are welded to a base
plate. Not shown, the gnomon tube goes through the holes in the thinner plates
and is welded to them. As I was saying, this thing could be
Hi John,
You actually have two questions here, and several engineers on the list to
answer them.
1) What should I do to prevent its deflection under its own weight?
2) What should I do to make it resistant to permanent deformation?
The answer to the second one is easy: make it out of the
Hi John C,
Off the top of my head, 25' between supports is going to be a bit long for 2
outside diameter in steel. 4 might do it, will have to lay some numbers on it
and quit guessing. Glad to hear it is supported at both ends. Supported in
the middle might be easier, but we like a
John C,
OK, here's a better deal for you. See attached spreadsheet.
Change the figures in black to reflect the tubing you like and can get.
Outputs are in red or blue according to whether your tube is simply supported
or rigidly supported. The truth will be in between.
Stresses and
Whoa, where'd spring go?
John B
...and, we are closer to the sun in our winter than
they are:)
Simon
--- Chris Lusby Taylor [EMAIL PROTECTED]
wrote:
I believe the sun crossed the equator earlier today,
so it's now summer here
in the Northern Hemisphere. Commiserations to
That's beautiful! Does it seem like the girl's torso might block light to the
dial?
John B
-Original Message-
From: Александр Болдырев [EMAIL PROTECTED]
Hi!
My friend Dr N. Mishik has found out in the Internet a very nice sundial
located
in Polotsk (Byelorussia).
I'm working on a direct south recliner for my latitude.
Since I don't have a PC, I don't have a sundial-
drawing program.? I used the low end of Vellum's
offerings to draw the attached which shows me
the proportions of the dial.? This is for 37.72N
and it reclines 25 degrees to give me an extra
Hi Fer,
Thanks!? People like you make all the difference.
I started years ago with just Waugh's book.? Did
not know of this mailing list.? Then when I had a
realization (an Aha!), I did not know if was right
or not.? It might be a very long time before I was
sure.
John
According to various books, one lays out the hour-line angles
of a horizontal dial for the latitude, one lays out the hour-line
angles of a direct-south vertical dial for the co-latitude, and
one lays out the hour-line angles of a reclining direct-south
dial for the co-latitude minus the angle
To pick a nit (though not sure if one's there to pick)
1080interlace is what's broadcast but 1080progressive
is what comes off a high def DVD such as Blu Ray.
John B
-Original Message-
From: Brooke Clarke [EMAIL PROTECTED]
To: John Carmichael [EMAIL PROTECTED]; [EMAIL
One might argue that the single page of cutouts
now provided is indicative of the level of effort
the school wishes to put into this subject.
Perhaps, then, we should design that page and
also provide two pages of explanatory material
for the teacher.? I think this is the best for which
we
Perhaps for a child of 8, a single-page explanation/illustration with cutout
dial at the bottom is the ticket.? Can it be done?? Then how about two pages?
John B
AOL now offers free email to everyone. Find out more about
That's cool.? The fellow with a Dobsonian wants a
low-height platform underneath his apparatus, and
so do thee and me.? So instead of a long arcuit
surface, he uses two short arcs.? Very nice.
Personally, I'm more of a purist, but for a fellow
who wants to match his watch time, this is a great
Hi Peter,
One more image, of the pivot alone?? Can't quite make it out in that second
view.? The rest is quite clear.
Question: Is it still a Poncet platform if it utilizes a cylindrical surface
rather than a planar surface?
Best,
John B
Peter Mayer wrote:
?
Hi,?
?
? I've tried
4/25.4 = .1575 inch
8*13+60 = .164 inch
That's not much difference at all.
(These are nominal, both will be under)
I would tap it out to 8-32.? It would
be easy to do with so little metal
to remove.? You're lucky it's close
to 32 TPI. (25.4/32 = 0.79 mm)
To get gnomons on in a repeatably
-Original Message-
From: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Wed, 18 Apr 2007 9:02 PM
Subject: A.Word.A.Day--gnomon
This week's theme: words for odds and ends.
gnomon (NO-mon) noun
1. The raised arm of a sundial that indicates the time of day by its
shadow.
Re: PDF size
Tony,
There is an option in the PDF writer to select the percent at which it
is printed. I use it sometimes to print very large drawings to 8.5x11.
It can also be used to print a slightly-large drawing to a smaller
sheet of paper. I wonder if that could be what you're running
Jim and John,
You know, I have questions about the orientation of the sat maps also. The
other day my wife was asking where something was on a hillside in a global
sense so she'd recognize that same hillside when we drive the curvy road in a
nearby park. So I got out my trusty Leica (nee
Well, I didn't want to get into this, but I have to comment that here we go again - stuff that definitely would not be a problem in person, that would be easily worked out, turns into a problem on the internet because people can't understand each other correctly from a few written words. We should
There are a limited number of entries at the bottom of this page which may be of help.
http://www.geom.uiuc.edu/docs/reference/CRC-formulas/
John B
-Original Message-
From: [EMAIL PROTECTED]
To: sundial@uni-koeln.de
Sent: Sat, 14 Oct 2006 7:25 PM
Subject: Slightly off-topic: names
I'm one of many more Mac users on this list than you know,
but I also have a PC; call me bilingual. There's one more problem
solved by going to zip and that's that the computer gurus at our
computer division really hate it when we download an executable.
These are some of the foremost IT guys in
Dear wecirp,
I'm not sure precisely what you're asking, sorry about my confusion, so
I'll just say a bunch of stuff and you can pick what you need and then
ask for what you _really_ wanted to know. May seem silly, but may
save time.
This is a horizontal dial so it should be installed such
Hi John C.
OK, right - that was the point about using a ball lens. A ball is
symmetrical in all directions so it will focus equally well whatever
the azimuth elevation of the sun. Here I'm envisioning a
ball lens atop a slender rod, so there is no blocking of the sun's rays
regardless of the
Hi John C,
I'd be tempted to use a ball lens if I could find one made of a
material of a low enough refractive index (and a high enough Abbe
number). Searching on "ball lens", I found a simple explantion:
http://www.edmundoptics.com/techSupport/DisplayArticle.cfm?articleid=245
The trouble
Hi Edley,
I did not have succes with a hollow glass sphere. Seemed like it
ought to have worked. Maybe I should take another look at
it. Glass has an index of about 1 1/2, water about 1
1/3, so water might fix what I ran into. Or I messed up.
Hi John C,
Jah,
image
Check out AOL.com today. Breaking news, video search, pictures, email and IM. All on demand. Always Free.
hollow_glass_sphere.gif
Description: GIF image
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
I got to thinking about refractive index on a theoretical basis.
Usually the way you beat refractive index down below the normal limits
is with porosity that is so fine that the light doesn't see it (e.g. AR
coatings). So what has high, fine porosity? Long period of
thought... Doh! Silica aerogel!
Daylight Saving Time?
John
-Original Message-
From: [EMAIL PROTECTED]
To: sundial@uni-koeln.de
Sent: Thu, 10 Aug 2006 1:17 PM
Subject: finding true north
Hello everyone!
I am constructing my first sundial
in my garden. I am having a problem finding true north.
Ah, another PC terrorist. But long before PCs copied the
look and feel of Macs, and even before AutoCAD, Apple's software
division created Claris CAD which will does more or less what Delta CAD
does, and guess what? It works well on 7.6 or earlier and also on
the latest classic. In between are
I am returning a compass sundial I received mail order today.
Markings and numbers for time and latitude are in the wrong
places. The bubble level is defective. The damping of the
compass needle is too low (that ain't ALNICO). I questioned
closely when I placed the order to determine if it was
Simon illustratingshadows wrote:
A number of those dials are poorly made, however some
of them have quite good workmanship. That good
workmanship is spoiled by consistently screwing up the
latitude scale, as well as other things. If they go to
the trouble to do good metal work, why not use
Would the clear coat have the same specular-diffuse quality as the
original paint or does it have its own type of reflectivity,
supplanting that of the underlying paint?
John B
Check out AOL.com today. Breaking news,
Tony Moss wrote:
I must admit that this is the first time I have encountered the term
'hard' anodising and the webpage referred to gave only general
information of the process.
Hard anodizing is still Al2O3, it's just extra thick. Can't get that
thickness by ordinary methods. I think by
If your weather includes years of wind with dirt in it, or godferbid a
desert sandstorm, I speculate the extra thickness of Al2O3 buffered by
compliant PTFE should hold up better than many things against the
kinetic SiO2, which I think is probably lower on the Moh's scale.
John B
Has anyone tried hard anodizing? I used to use tefloned hard anodizing
on 6061 for mechanical parts subject to sliding. It has a duller,
grayer finish. I wonder how it does in the weather. I have regular
anodizing, water sealed, on my 12 (30 cm) bowstring equatorial. Fine
weather
Larry McDavid wrote:
I have a 1-inch thick 6061 machined aluminum tooling plate
mounted in a polar plane in a local desert at 4500 feet elevation
where the UV exposure is extreme. This plate was hard black
anodized and Teflon impregnated when fabricated 23 years ago.
Today, it is still shiny
Now if they'd just put the a.m. VI diametrically opposite the p.m. VI...
John B
-Original Message-
From: Robert Terwilliger [EMAIL PROTECTED]
To: 'Steve Lelievre' [EMAIL PROTECTED]; sundial@rrz.uni-koeln.de
Sent: Wed, 17 May 2006 09:48:08 -0400
Subject: RE: Sundial Motif to Be Featured
Can you tell I'm recently retired, with feverish mind? Or more
prosaically, I'm exploring fabrication methods now that I have more
time. But I digress.
I just recalled that our local park district has amongst its many
facilites a place to cast jewelry by lost wax. The hobbiest can do
gold
Is there a formal taxonomy for sundials?
I like:
http://sundials.org/faq/
select:
6. What types of sundials are there?
I was thinking about my bowstring equatorial. It's also an
equinoctial, right? So what takes precedence? Seems like it would
help the new guy ('tis I) to be able to look
I am in need of the help of a big-brained list member, as I can't quite
figure this. I know of the ecliptic and the celestial equator and the
precession of their crossing and such, so I presume I have necessary
but insufficient background.
OK, earth's orbit, plan view, looking down at the
Hi Joe,
By plan view of the earth's orbit, I meant the plane of the earth's
orbit is in the piece of paper we are looking at. The axis of the
earth is tilted with respect to the orbital plane, therefore it will
project a line onto this piece of paper. So my question was, where is
this line
After looking at the dial plate closely, I was able to see where the
gnomon had originally been, many many years before. I agree that it
was probably set where it is now by a repairman with more aesthetic
than sciatheric sense.
I'm leaning more toward your point of view - a friend suggested
Yesterday I visited the 15-inch-diameter bronze dial at the Filoli
Estate in Woodside, now run by Filoli Center in conjunction with the
National Trust for Historic Preservation.
I found that the best fit to the dial's hour lines is 50 N. The gnomon
appears to have been cut down to 46.5 N
This is fascinating. What is the central figure doing? What methods,
instruments, is he using? Why does he have two great toes on one foot?
But seriously, I am interested in old methods; just don't know much
about them.
Thanks,
John Bercovitz
Enough to make anyone covetous. I wonder what the optics inside the
oculus are. Seems to have a healthy aperture and a very wide angle.
Also, at noon there seems to be a dark streak in the middle of the
beam. Might be a rod crossing the optic at some distance.
Cool!
John Bercovitz
Robert
Here in northern California, seems like we have lots of trees. Few
good sites for sundials in populated areas near me because of this. I
was thinking I need a sundial site examiner. This would be a device
that would scan the path of the sun over the sky looking for
obstructions. It would
Just got a chance to sketch up a thought that might be easy to build.
At the bottom is a clampable pivot used to set the red pole axis to 37
degrees, in this case. The blue semicircle is clamped to the red pole
axis and does not rotate about it. The blue semicircle has times
printed
on it,
I've gotten a number of comments off list on the gadget. Let me first
say thanks to all.
While designing, I was thinking along the lines of something Dick said
off list which is that there was something ST sold which was a polar
axis with a sight-along pointer pivoted on it and you could set
Douglas Bateman [EMAIL PROTECTED] wrote:
I have a site on my browser, www.mapmaker.com/shadowfacts/sunweb.asp
that shows the terminator throughout the year. It is fascinating to
see how
rapidly the shape changes,
Already the sunclock shows the light is broadening in the northern
This is really a gedanken experiment as I know no one at high latitude
needing a dial, but here's what I came up with for a dial primarily for
high latitude. The dial has a square gnomon and four sets of hour
lines, one set for each style. I'd be interested in the list's
comments on its
Chris Lusby Taylor [EMAIL PROTECTED] wrote:
It seems to me it would work, but I can't see any advantages over
a cylindrical gnomon.
I was thinking an edge would give better definition of the position
of the shadow, at least for a stout gnomon. But outside of that,
I agree with you.
The idea
Chris Lusby Taylor [EMAIL PROTECTED] wrote:
It seems to me it would work, but I can't see any
advantages over a cylindrical gnomon.
Aha! It dawns on me now what you were saying. I
thought you meant tell time by the center of the
shadow of a small-diameter gnomon, but you're
suggesting
I second the motion to experiment. I have heard that black-oxided
stainless is no longer rust resistant. Am dying to know if this is
actually true.
John Bercovitz
-Original Message-
From: tony moss [EMAIL PROTECTED]
To: Sundial Mail List sundial@uni-koeln.de
Sent: Sat, 4 Mar 06
John Carmichael wrote:
I heard that you can't laser cut stainless steel because the light
reflects back into the machine
and it either doesn't cut or it doesn't cut well. Is that true?
Steel and especially stainless are pretty good because they are dull
enough. Aluminum is more trouble
In a message dated 2005/04/19 12:23:22 PM, [EMAIL PROTECTED] writes:
Yes, the U.S. Congress is presently discussing whether to extend DST
from the first Sunday in March to the last Sunday in November -- an
increase in the duration of DST by about two months.
I hope they pass the
Well, here's another question. I've been thinking (again) about
what a proper shadow would be for a bowstring equatorial or a
hemisperium or hemicyclium. I made up a dumb little spreadsheet
which is at the URL below to thrash about with the numbers some.
Parts of that spreadsheet are shown
Hi,
I stuck a tall nail perpendicularly in a horizontal board
for the equinox and I marked the position of the shadow of
the nail's head several times the day before and the day
after the equinox (the equinox was in the middle of the
night for California). I got two parallel tracks very
Is there an approximate formula for the declination of the
sun vs day number? I just tried the obvious
=23.44*SIN[(day number)*360 degrees/365.2422]
but it's not too shiny - misses by a degree or two at times.
Thank you,
John Bercovitz
38 hours, 35 minutes counting...
-
I was thinking about another dial, one that does date and
time whenever the sun is up. I came to the conclusion that
a hollow hemisphere with its lip in a horizontal plane and
nodus at the center of the hemisphere would do it, and might
not be too difficult if I could make the hemisphere
Thanks for the pointer to GPS-Nv99_Innov.PDF
It was gratifying to learn that UTC and sundials
always agree well, given the usual corrections
between sundial time and UTC.
I didn't quite understand the advantage of periodic
insertion of leap seconds vs aperiodic for the
correction of the ~2msec
In a message dated 2003/11/27 02:50:54 PM, [EMAIL PROTECTED] writes:
BBC Radio 4 will carry a 30-minute show on sundials on Saturday, 13
December at 1530 GMT.
It's of course easy to hear in the UK, but anyone with a Web
connection who can stream audio can also listen at
Many thanks to all! Just checked - nothing happening at 198 kHz except
heterodynes and voice I can't make out at this time here at 37.7N, 122.1W.
(not that I seriously expected to be able to hear anything in the longwave
bands at this distance)
Thanks again,
John
-
For those interested in a report, I laid two courses of brick last weekend
(which made me a weakened weekend warrior). I figure the first course
will settle and then I can shim the gap between the first and second courses.
The plinth was actually an annulus, a short section of thin-walled tube,
Many thanks to all for the great suggestions as to how to
stabilize a plinth and still be able to remove the installation.
Also, Tony Moss' discussion about that dead spot in the dial
when the gnomon doesn't have a knife edge or zero thickness
was timely. When I was figuring the dial plate's
., I would be interested in what they
consider the optimal dimensions for the pin hole vs. the
size etc. I will install one tomorrow at my home,
commemorating the Spring Equinox.
Here is perhaps a different way of thinking about the
problem of the hole diameter vs its
I had to back off on my grandiose plans, which you folks kindly
commented on earlier, and scale the thing down to something I
could easily build. Results, for the curious, are in the sundial
section of my website:
http://www.angelfire.com/ca2/tech3d/sundial.html
Comments always welcome!
John
The photo-3d list people maintain a different list sell-3d for
commercial postings.
That was a long time ago and I'm trying to remember why I did that.
I think it was for two reasons. The primary reason was that the
main list was overloaded with a horrendous amount of traffic. A
secondary
I love this list's digressions! 8-)
Trivia question:
You can't join a straight road to a circular road tangentially
else the third derivative (d/dt of the centripetal acceleration)
will be infinite. So, what curve is used to join the straight
road to the circular road?
If no one knows, I
If brass numbers are epoxied to marble stone, will
their different coefficients of thermal expansion
break the bond?
Sorry to be coming in so late on this. Work pressures -
got to go there five days a week and work eight hours (or
more) too. Ridiculous!
This is a transient thermal
In a message dated 2000/02/15 01:44:39, [EMAIL PROTECTED] writes:
The way to cut the Gordian knot is to throw out everything and start
over with a base 12 numeral system. Then the scientific calculations
and the everyday divisions by 2, 3, 4, and 6 are *both* easy.
Hear hear! The greatest
Like most engineers in the US, I use both systems. Here are some
random observations from a few decades of engineering.
There are very few arguments in favor of American (nee Englsih)
units other than avoidance of the the cost of conversion. However,
it is interesting that the English system
When I first started using cables for my styles I thought a lot about what
would be the correct diameter cable. On one hand, I wanted the cable to be
as thin as possible, because a thin shadow gives a more precise time reading
than a thick one. On the other hand, if the shadow is too thin,
Do you know of any kind of formula to estimate the proper proportions for
seeing high or distant dial lines, letters etc. clearly? I suspect
architects, engineers and advertisers (billboards) must have some way of
knowing what will be clear to a given eye at a given distance.
The best the
In a message dated 99/12/11 10:53:47, [EMAIL PROTECTED] quotes:
Since a full moon on the winter solstice is occurring in conjunction
with a lunar perigee (point in the moon's orbit that is closest to
Earth), the moon will appear about 14% larger than it does at apogee.
This will make it appear
Well, that was fun,... and useless. I took a miniature
fire hose nozzle which fits on a garden hose and measured
flow rate when it was in the water in the bucket and out of
the bucket. No difference. I measured reaction force when
the tip was at various depths in the water and when it was
I had a spare moment at work so I looked up jet boats
in Mark's Standard Handbook for Mechanical Engineers.
The thrust is m dot *(Vjet - Vboat). This is derived
from impulse-momentum which is a sort of rearrangement
of the common formula from Sir Isaac,
F = m * a
to:
f = m * dV/dT
to:
f dT = m
Waugh gives Feb 29 for both EoT and declination of the sun in tables
in the back of his book but I'm not sure what is going on here. For
instance, declination:
Date decl delta
February25 -9 24
22
February26
I have detailed the parts and put them up on my web site.
http://www.angelfire.com/ca2/tech3d/index.html
Would appreciate any comment. They're in .pdf again.
Thanks,
John B
But in the case of sundials which use strings, cables, rods, or pipes,
wouldn't the gnomon be the SAME as the style because the center of the
whole shadow is used to tell time, and not just the edge?
I was thinking about this the other day. Wouldn't you read the time at
the center of the
Many thanks to those who answered my question on and off the list.
Is there a book which describes the slider version of the perforated
ring dial? I would like to know how the date scale is usually laid
out for this type of perforated ring dial. I have laid out several
schemes now, but do not
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