Fer,
Here is, I think, the message Mac mentioned.
Bill
-- Forwarded Message --
From: "fer j. de vries", INTERNET:[EMAIL PROTECTED]
TO: "Shadow Maker", INTERNET:[EMAIL PROTECTED]
"sundial", INTERNET:sundial@rrz.uni-koeln.de
DATE: 3/26/01 7:21 AM
RE: Re: Recli
Hello Frank,
In your consideration of vertical dials, you might find it worth
pairing the south dial with its north twin. Particularly at your
fairly high local latitudes, that allows showing the summer sunrise
and sunset times, when they are often of interest. After all, given
the frequency of
Mike,
The good old Pythagorean Theorem can serve. In the attached
figure, , in orthogonal coordinates with axes N-S and
E-W (could be Y, X ) R is the radius from point C to the East.
For an increment n toward the North, there will need to be
incremental movement to the East e if the circle is
Dear List Subscribers,
I propose a challenge to the tinkering gang:
Devise and BUILD a dialists' (i.e., shadow-observation-
based) method to measure the apparent angular diameter
of the sun, and to compare its values at the two solstices.
No glass, or specular-reflective, image-forming elem
John Davis wrote:
>The info you want is in the BSS Glossary (plug, plug!) under
"semidiameter".
>The answers are 15.76 arcmins in July (aphelion) and 16.29 arcmins in
>January (perihelion). For the purposes of looking at sunspots, I'd say
this
>was insignificant. If the differences were much la
Claude, et.al.,
Claude Hartman wrote:
>.. There seems to be continuing concern for the
>use of this name. As before, there seems to be no other
>reason to refer to these non-linear gnomons as "bifilar"
>other than the total lack of any better terminology! .
I don't know tha
Fellow dialists,
Re:
> >In regards to finishes friendly to shadow definition: matte white is my
> >choice.
>>
>>I don't think anyone could disagree with that.
>>Chuck Nafziger
>Well, you might consider a slightly darker colour like sand or beige. My
>experience is that when you use white the
Arthur Carlson wrote:
>"fer j. de vries" <[EMAIL PROTECTED]> writes:
>> Some members of this list have drawn an east-west line at the september
=
>> equinox.
>> But what accuracy this line will have?
> >
> >Assuming a perfect horizontal plane, ...
> >...
> >A line between these 2 points has an a
Fernando,
Here is a small GIF to illustrate the concept. It
is a nice example of symmetry. The thick lines
represents the "rope," and the little squares show
where it is gripped and marked.
Bill
Attachment converted: Macintosh HD:R-ANG.GIF (GIFf/JVWR) (0001BF30)
G'day Maria,
A 'classic' thing to do on an equinox, is to mark, (pegs in earth --
chalk, sticky tape, etc., on the patio paving, -- or as your imagination
suggests) the location of some well defined fixed object's shadow
on any horizontal surface every-so-often for a goodly span of the
day's
Vanderlei and others,
Please forgive my previous incomplete transmission on this topic:
>Vanderlei Borsari wrote:
>>I have a doubt and I hope someone can help me: I would like to make a
>>Shepherd´s (cilyndrical) dial, and I found the following equation to
>>calculate the size of the gnomon:
Vanderlei Borsari wrote:
>I have a doubt and I hope someone can help me: I would like to make a
>Shepherd´s (cilyndrical) dial, and I found the following equation to
>calculate the size of the gnomon:
>G = H cot(113,5º - lat)
>Where: G is the size of the gnomon
>H is the height of the dial sca
Allan,
There is the alternative of stellar observation, i.e.,
Polaris, and the other circumpolar visual stars.
A fairly simple setup of fixed concentric-rings or a
pin bar as fore-sight, and an adjustable position
rear-sight should, over a couple of nights of
converging approximations, serve
Dear Jorge, John, et.al.,
I realize I should have sent it as e-mail text in the first place.
Here is the listing for all those who couldn't make use of my
ancient Q-Basic, or just want to see the pardigm:
REM Moon Calendar
On Fri, 21 Jul 2000, Dave Bell wrote:
>On Fri, 21 Jul 2000, Richard Koolish wrote:
>> People on this list may be interested in the Moonstick
>> slide rule moon phase calculator.
>>
>> www.moonstick.com
>>
>Wow! Or, shall I make that Wow! to the 4th power? (W^4)
>Wonderful concept!
> Beautif
Bob, Steve, et. al.,
I have no knowledge of the origin of the practice of using
zero to mark noon, but there is as much logic as for
twelve, since it is the beginning, or "zero," for P. M. hours,
and so can be expected to precede hours 1, 2, etc..
by an hour, especially with the sun's merid
-- Forwarded Message --
From: Wm. S. Maddux, 75211,2555
TO: John Carmichael, INTERNET:[EMAIL PROTECTED]
CC: SUNDIAL, INTERNET:SUNDIAL@RRZ.UNI-KOELN.DE
DATE: 5/6/99 2:46 PM
RE: Copy of: RE: a peculiar sharpener
John,
Here is my interpretation of what is going
Hello Gianni,
Thank you for your clarification of the matter of the
bead-and-hole shadow caster. Your plottings of
the light distributions should help to convince some
disbelievers as to the physical mechanism of the
formation of the shadows.
At the time of posting this note, I also will forwar
Dear Gianni Ferrari,
You wrote:
>I have read with a lot of interest the numerous messages
>dealing with the azimuthal sundials and I have noticed that
>sometime there is a little confusion on the names that we
>use for the different types of sundials. I write you my opinion.
> .
Hello John,
The shadow plane for a given hour angle is uniquely
defined by the sun's center and the polar stylus.
(A line, and a point not lying on that line, determine
a plane.)
Since, as the shadow plane for a given hour angle is
always the same (the reason for using a polar style)
its in
Please all, especially those south of the Equatorl,
The paragraph:
"(Southern hemisphere dwellers may insert a line
ahead of the CIRCLE commands as shown here:
Rkx = -Rkx : Rsx = -Rsx
CIRCLE (320, 280), 170, 13
CIRCLE (Rkx, Rky), 3, 15
CIRCLE (Rsx, Rsy), 3, 12: PAINT (Rsx, Rsy), gs, 12
to ha
List Members,
On 1/28/2000 Fer deVries wrote:
>...In Amersfoort recently a sun pointer is erected. It
>is a mechanical driven and computer controled arrow that
>always points to the sun, during the day and the night, in all
>kind of weather, cloudy or clear.
>A picture of it may
Dear Fernando,
>> You don't need a nodus, but just a vertical rod in the center.
>> Read where the shadow of the rod intersects the circle of the proper
>> date.
>> At low latitude this type of dial isn't very useful.
>>
>> Best, Fer.
>Maybe with a very tall rod?
>- fernando
Beginning on p.180
Dear Rudolf,
"Tyro" appears to come from the Latin, "tiro" meaning recruit.
In English, a newcomer, beginner, novice, especially one just
starting to learn.
Bill
Tony et al.,
In Volume 2 (Mechanical) of "Advanced Telescope Making
Techniques," Selected Articles from the Maksutov Circulars,"
Edited by Alan Mackintosh*, Chapter 10, "The Telescope Maker's
Workshop," there is an article titled, "Anodizing For The
Amateur Telescope Maker" by Maurice V. King.
Dear all,
Alhough in response to comments re NASS and its journal,
the Compendium, this is an attempt to speak to the dialing
community at large, as embodied by this list, and by the
various societies, clubs, etc.:
There is a somewhat wry comment, often repeated at back-to-
school time by tho
List participants,
Who will join in a word of thanks for Tony- "The Voice of Reason"- Moss,
who went straight to the point, and offered a solution to the problem?
Blessed are the peacemakers, especially the practical-minded ones.
Bill
I have had success in fastening mounting screws into carved
limestone to attach it to a separate stone base, by using
silicone caulking compound. The type sold for sealing bath
fixtures is available in transluscent (cloudy gray) or with an
opaque white pigment. This type may be sold in squeeze
Chris Lusby-Taylor wrote:
>I find the quarter day argument rather nit-picking, and irrelevant over a
>span of, say, four years. But the eccentricity of the earth's orbit, with
>perihelion very close to a solstice, makes the northern winter / southern
>summer significantly shorter than half a ye
In my earlier response to PsykoKidd's question:
>To paraphrase: The question was, "Over the span of a year do all
>places on earth recieve on average exactly 12 hours of daylight
>and 12 hours of night."
I erred in my example. It should have read:
Example: At a point on the equator where
PsykoKidd questions a 'yes' response to:
>To paraphrase: The question was, "Over the span of a year do all
>places on earth recieve on average exactly 12 hours of daylight
>and 12 hours of night."
(The phrasing in the Sunday weekend paper was a little different:
"... Does the sun shine equal
Tony et al.,
I've tried to duplicate the 'Moss Effect' using four different
nozzles, and buckets ranging from nominal 3 gallon (U.S.,
not Imperial) down to less than 1 gallon capacities. At no
time did I observe anything I could interpret as reversal of
the 'reaction effect.' All 4 nozzles we
Attached is a sketch of the kind of pen mentioned in previous mail.
Perhaps it will help in searching for such a pen in secondhand shops.
1519 bytes
Bill
Attachment converted: MAC Hard Disk:BOWPEN.GIF (GIFf/JVWR) (00017DF3)
Guido,
>after some efforts i have calculated my vertical declining sundial, and it
>seems to work fine.
>Now I have the problem to draw the final hour lines on the preliminary
ones
>(drawn with a pencil), but the wall surface has many granules and it is
>difficult to obtain sharp edges for these
John B. wrote in part:
>There is a sundial which is a disk with a rod for a gnomon running
>perpendicularly through its center. I understand the problem is that
>it can only be read from the top in the summer and the bottom in the
>winter. Has anyone tried making the dial of acrylic/perspex/gl
Tony Moss described:
>..snip... a "Portable Heliograph Set' in a pouch. It was
>simply a mirror about four inches across with a sighting
>hole in the middle. A length of cord attached it to a short
>rod with a bead on top. ... snip ... It all seems rather 'iffy'
>but I suppose was intended
Tom,
You wrote re the editors of "Popular Electronics:"
> They were out of their league in the area of sundialling. . .a
>typical situation amongst many techno types--to know all there is
> about one subject, and not have the foggiest notion of anything
>else.
I think it is attributabl
A couple of schemes for safely viewing the sun's
projected disk:
1.) Use a small piece of ordinary looking glass
as a "pinhole" to project the image onto the
shady side of a building or other screen. (This
is a sort of, 'steerable shadow-sharpener.') Holes
of various sizes can be made in piec
Roger Bailey wrote:
> I recommend the old Air Force Survival Manual (AFM 64-5).
> ...
Art Carlson wrote:
> ... And if the shadow is oriented straight up and down,
>then the moon is in the south. You don't need to know
>much more than that to find the nearest road.(*)
As a biologist, I'd lik
>I too would like to see this sundial, which seems to be so universally
>known. If anybody does have a pic, please send me a copy ok?
Jim,
I don't have a picture to send, but if you can access the book,
look in Waugh, at pages 33 and 34 of Chapter 4, 'The Equatorial
Sundial.' The lower pho
John,
Here is my interpretation of what is going on
with the bead and hole shadows:
First off, any attempt to estimate the center of the
'fuzzy' edge shadow of a style's edge is subject to
uncertainty because of the properties of the eye
and/or visual system. The eye is able to function
over a
To all:
As soon as I launched my previous note, re: Shadow Sharpener,
I realized I had failed to attach the GIF image file ...
1627 bytes.
Here it is: (pinhole compound solar telescope)
Bill
Attachment converted: MAC Hard Disk:PIN-HTEL.GIF (GIFf/JVWR) (00015069)
Gordon,
>Roger, thank you for your post. The Shadow Sharpener being a pinhole
camera,
>why not replace the gnomon with a pinhole? One then could center a circle
on
>the image and determine the time from its position.
Some years ago, when thinking about heliochronometers, I realized that the
s
Peter Tandy wrote:
-- I don't know too much about the radio side of quartz production, but
it was
needed during the war to make oscillators for the radio industry (and
military, of course). These plates must be cut at a highly specific angle
from a certain part of the crystal. ... .
Patrick Powers reports:
>I sent them a message and got the following reply:
>. Price in UK is £747 and cards are £56 / 200...
>A tad too expensive for me though Patrick
I suspect more than a tad too expensive for most of us.
Besides, where's the fun in b
Greetings all,
Re cross-cultural pedagogy, etc.: Back in the late '60s- early '70s,
I lived in Puerto Rico, doing my own research in marine biology,
teaching graduate students, and advising them in their theses'
research. Although our grad. students preferred instruction in
English (almost
John Hoy,
I'm not a Postscript user, but if you are programing to design Capuchin
dials, you presumably have available provisions for the scale of hours,
solar declination, local latitude as independent variable, etc.. You can
get the line you want by ploting time vs declination via:
co
Re the hour limitation line/curve for a Capuchin dial,
John Hoy wrote:
> Is that line an arc of a circle?
Fer de Vries wrote:
>The line through the endpoints of the date arcs
>isn't an arc of a circle.
>I calculate or construct a number of endpoints and
>connect them to a smooth line.
I bel
To Malcolm Purves and all list members,
My apologies if I misinformed when I repeated that theory of
French vs English translation as explanation for why UTC, not
CUT. The version I offered was as told to me some years ago
by a Canadian physicist acquaintance. It never occurred to
me that a
Malcom Purves asked:
>UT once upon a time(ho!) was UTC , Universal Time Coordinated
>who messed up on the word order ? Why not Coordinated Universal Time ?
>CUT ?
Those initials were assigned in French. The official international atomic
time scale is maintained by the Bureau International de l
Frank Evans et al,
> The watch from midnight to four in the morning is
>called the middle watch, .
According to American nautical "folk-etymology," that middle
watch was dubbed the "gravey eyed" watch, referring to the
bleary, gummy-eyelidded state of those wakened in the
Dear Tony,
You wrote:
> ... snip .. Suggestions for potential judges would be especially
welcomed.
I would like to propose Paul Murphy for a judge. He is of a culture
renowned
for its poets and wordsmiths. His profession has given him insight into
the
onus and honor of the judicial role. It
Dear Dr. Carlson,
>Have you considered replacing your analemmic cut-out with a solid of
>revolution? It simplifies the manufacturing and operation of the
>dial, but it does introduce errors of up to 1 min 30 sec because the
>exact analemma is "tilted". This type of dial was apparently invented
Arthur,
I'm not sure exactly what self-set rules you are playing under. If you
allow a timepiece, (it needn't be a very good one, nor set to Greenwhich
convertable time,) and you can get two equal length shadow timings (in
relative time) on either side of any day's MARKED shortest shadow regio
Tony,
ATM - Book One, ("Amateur Telescope Making"), A G. Ingalls, Ed.,
Scientific American Press, may be the book you remember using.
You can also find instructions in older editions (into the 1950s,)
of the "Handbook of Chemistry and Physics," Chemical Rubber
Publishing Co..
Good Luck with
Dear Pieter Liefooghe,
I owe you, Fer deVries, and the List an apology for not repeating
Fer's comment, in my response on the term for the highest point
reached by the sun on any day. Fer wrote:
> .. snip ..
>In literature sometimes is written that on a certain day, when
>t
Dear Fer,
In English the term for the highest point is "culmination," specified
as "superior" or "inferior" for a particular meridian's plane. For
example: Greenwich inferior culmination by a fictitious mean sun
defines the 0 of UTC, the Greenwich superior culmination (noon)
marks 12 hours
Rudolf Hooijenga wrote:
>I have often noticed, while viewing an ordinary television set, that if
>I turned my head sideways I could easily see the lines making up the
>image, where while I watched the screen in the normal way, they did not
>bother me at all.
>In other words, the same lines that
All Members of list:
Please forgive an elision in a message I mailed today, a little over an
hour ago.
In the passage on using a sextant as a "sundial." I wrote:
" (Note that depending on the size of the eye-piece aperture and
distance of the eye behind it,, you can easily get resolution
Chris Lusby Taylor wrote:
>Bill Maddux gives a very logical reasoning to the subject of how
accurately one can read a sundial, assuming the >reading is of the centre
of a symmetrical shadow line with fuzzy edges.
>I am inclined to agree that judging the centre of such a shadow must be
easier tha
Hello Mike,
You wrote:
>The only thought I had was that the line will not be a straight line at
>higher latitudes but a curve of some sort.
Your supposition that the line curves is correct. Except at the equinoxes,
when it is a straight east-west line. Otherwise, it is for us North
Americans
Tad Dunne wrote;
>I suggest a good measure is not the largest dial but the most accurate to
the
>naked eye. Some really big ones might fail to take the equation of time
into
>account. Small ones with an analemma might read to the nearest 5 minutes
or
>so, while larger ones with an analemma mig
Fellow Dialists,
Since the question of the "World's Largest Dial" has been recurrent on the
list, might I submit that the largest is an (approximately) spherical dial,
a little more than 12,700 kilometers in mean diameter, and is located here.
(Wherever you choose to designate "here.") As with
Hello Ross and other list members,
Dr. McCluney asked:
> If you use a slide projector with a half-degree circular aperture
stop
How many millimeters diameter of a circular aperture stop will produce a
beam spread of a half-degree? If the focal length of the projection
lens is f in millimete
Dear Tom,
So far on the list, various suggestions have addressed simulating the
angular size of the sun's apparent disk as a source, but if you are
interested in the geometry of the actual dial-style system as a whole, you
must deal with the problem of the optical distance of the sun. For
examp
Dear Fred,
You wrote:
"There was also an article (with cover photo) in a 1975 issue of Sky
and
Telescope. I can't locate my copy at the moment, so I can't give you the
specific issue. I subsequently had a letter to the editor printed in the
Dec 1975 issue [50(6):355,382], pointing out how t
Dear Tony,
You mentioned that you needed log tan values for "one remaining job,"
calculating the sun's azimuth. Are you by any chance using the equations
from Waugh's book as shown on page 92? If so you are unnecessarily
getting involved with logs.
You can do the same calculations using your
Dear Jim,
>An artist friend wants to make a sundial of a particular design,
>which he describes as a "globe sundial designed by Thomas
>Jefferson". the rough sketch he sent me suggests that the dial
>face is carved on a spherical surface.
> -- if anyone recognizes this design and can direct me
1997 Greetings, Roderick and other List members,
Roderick Wall wrote:
>Thought that you all may be interested in a window 95 software
>program (AtomTime95) that you can use to set your PC clock on
>time. So that when you use the NASS's Dialist program your clock
>will be on time.
>The URL addr
Dear Mike,
>Ferric chloride is tricky, but preferrable to messing around with
>acid. I find that getting a good quality etch resist is of
>paramount importance. The photographic process is tricky, but
>with a lot of trial and error good results can be obtained. Like
>anything, the more you do,
Ciao Angelo,
You asked:
>To all sundialer
>if a wall is not lighted at 12 am, how can I know its
>declination whitout
>magnetic compass ? (12am is obviously the local hour).
>Thankyou to all
>Angelo Merletti
Whenever the sun does conveniently shine there, mark the
position of the shadow cast
G'day again, Roderick.
Two-arm and three-arm protractors may be had from marine
instrument dealers, as well those who supply tool and die
makers. Bought new, they are quite expensive, and while
you might find used ones in some seaport-city hock shop,
chances of doing so are not good.
Tool makers
The following text was originally sent to Dr. Arthur Carlson
but not to the rest of the sundial list-members on 8/22/96.
As Dr. Carlson placed his response to this on the list
8/23/96, I thought that the next exchange(s) would be more
intelligible to others if this message were avalable to them.
Hi Art,
Re your rhetorical:
>You just wanted me to say "literal equinox"?
No, I just wanted to pass on something I learned when I
computed the time at zero declination in an attempt to
get the Autumnal Equinox value for 1997 in connection with
Bart's wedding query. When I compared my result wit
Cheers Roderick,
In SKY and TELESCOPE, V:44, No.1, pp(20-22), there is a
piece, "The Shape of the Analemma", by Bernard M. Oliver,
that may help you to "see" the basis of the tropical
component of the Equation of Time. The first figure and
caption on p21 will especially repay careful study.
Ston
Mark Gingrich asked:
> .. Are there any other cathedrals in Europe that
>emulated the noon mark in the Church of San Petronio,
>Bologna, Italy?
I don't know if you would call it "emulated", but in
Vol. 50, No. 6 December 1975 p.369, there is a photo
accompanying an article, "A Design for an
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