Monte Castello monument
Ciao everyone! I have been contacted by a brazilian architect who is in charge of building up a monument in the Italian Apennino between Florence and Bologna to commemorate the battle of Monte Castello (44°12'12''N 10°57'18''E) during WorldWarII fought, with heavy losses, by the "Força Expedicionària Brasileira". I have been asked to put down a shadow reference to the day of the victory. I am particularly interested in giving my help because at the time of the Monte Castello battle I was a young man and lived not too far, in the Bologna plain waiting for the liberation from the German troops. If someone is interested in details of that war event and in the image of the scale model of the monument (no more than 20Kb in all), please let me know. Ciao Angelo --- 44 32' 10''N11 32' 15''E ---
Commercial Offerings
I side with Fer, Bill and John. To me the solution suggested by Fer seems to be acceptable as it informs without being invasive. Ciao Angelo Brazzi --- 44 32' 10''N11 32' 15''E ---
Re: Rod Gnomon Hole Placement
John Your message and especially the attached draw recalls to mind that in my site: http://web.tiscali.it/partena/index.htm I have published a short note (alas in italian!) on the theoretical problem of inserting a cylindrical polar gnomon into a wall. As the lecture of the hour is made with reference to the center of the gnomon shadow, the axis of the cylindrical polar gnomon should coincide with the center of the sundial, that is the point where meet all the hour lines. The intersection of a cylinder (the cylindrical polar gnomon) with a plane (the wall) generates an ellipse. The center of the sundial should coincide with the center of the ellipse. Once you have fixed the gnomon to the wall that coincidence point is hidden. I was interested in calculating the distances of the orizzontal and vertical tangents from that point, in order to use them in the program for calculating the coordinates of the points of the hour lines with reference to a system using those orizzontal and vertical tangents as xy axis. In the same note I pointed out (and this might have some reference to the content of your message) that in the case that the sundial shows also the solar declination curves, it should be taken into account that the material length of the the cylindrical polar gnomon is longer than the theoretical one by: d/(tan lat * cos decl) where d is the radius of the cylindrical gnomon. Ciao Angelo At 08.11 01/08/03 -0700, you wrote: Hello All: Because of the importance of rod gnomon attachment on stained glass sundials and the interest in the subject, I thought I'd make a Delta Cad scale drawing for the website showing a sideview of the hardware used to attach it to a pane of glass, using the bolting method. Before I made the drawing I already suspected I see one very interesting detail. This may come as a surprise to most of you, but the drawing clearly shows that the center of the sundial, where the hour lines converge, IS NOT where you drill the hole in the glass! This is true for all those bent rod gnomons that are not perpendicular to the dial face. And it applies to all sundials with bent rod gnomons, not just stained glass ones. In my drawing, I used 1/8" (3mm) thick glass, 1/4" (6mm) thick rod gnomon, 1/2" padded and flat washers, and 1/4" nuts. You can see that the glass hole is .371 inches (9mm) below the dial's center. This is an important design consideration that the designer must consider in his plans. John John L. Carmichael Jr. 925 E. Foothills Dr. Tucson Arizona, USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Sundial Sculptures Website: http://www.sundialsculptures.com Stained Glass Sundials Website: http://advanceassociates.com/Sundials/Stained_Glass -- Angelo Brazzi mailto:[EMAIL PROTECTED] http://web.tiscali.it/partena/index.htm
Re: Painting Dials
Dear Claude This is technique I use on plastered wall. To prepare the wall I just treat it first with sandpaper. In the case of a nonpainted new wall just to remove the loose particles of sand. In the case of a wall which has been already painted this treatment removes most of the previous paint. The result is a porous surface, not waterproof and sufficiently smooth to receive the signs of the pencil. Then I treat the surface with acrylic resin diluted with water 1:3 1:4. The solution penetrates into the outer layer of the wall thus improving the adhesion (for affinity) of the subsequent acrylic colours. I make use of a limited number of light resisting acrylic colours. That is those in which the pigment is mineral, avoiding the ones of organic nature. To obtain light watercolour effects, I dilute the colour base with the acrylic resin diluted in water. No final treatment. Acrylic resins let the wall "breathe", and the moisture can freely pass through the layer of acrylic without forming bubbles. Sundials made some 20 years ago are still in excellent conditions. Some fading in case of organic pigments, but this add a flavour of antique. Angelo At 11.32 13/10/03 -0700, you wrote: I am looking for suggestions for my column "Back to Basics" in the NASS Compendium. I want to write about painted sundials for the beginning dialist. ..... --- Angelo Brazzi mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] http://web.tiscali.it/partena/index.htm 44 32' 10''N 11 32' 15''E ---
Sun declination 1693
To them all involved in calculating sun declination for April 18, 1693. I want to thank all of you for the help given to me. The reason of my request was that I have to cooperate in restoring the main square of a village the foundation stone of which was laid at half an hour after noon of April 18, 1693. I have calculated the sundial in the middle of the hexagonal square and I have been asked to indicate the point where the stylus would have cast its shadow at the exact moment of the foundation of the village. As I have to document in writing the calculation I cannot assume for this purpose an out-of-date sun declination. Thanks. Angelo Brazzi If someone is interested in knowing more details of the history I have resumed above, please contact me at [EMAIL PROTECTED]
Sun declination 1693
Someone has asked me for more details on the above subject and has suggested
to send them to all subscribers.
There was a village in Sicily (Italy) of very ancient origin (presumably
Echetla existing before the Greeks came to Magna Grecia) called Occhiola' .
In 1693 it was completely distroyed by the terrible hearthquake of Noto Valley.
The local Prince, Carlo Maria Carafa decided to build up a new village in a
safer place not too far from the ruines of Occhiola' to collect the survivors.
According to the historical sources, on Saturday April 18,1693, at half an
hour past noon he laid the foundation stone.
The plan of the new village, called Grammichele, (14° 38' 11" East Greenwich
37°12'51" North) consists of a series of concentric hexagons with a central
square perfectly hexagonal.
In the center of the square there was an horizontal sundial with "italic"
hours deferred of half an hour ("ore della campana" hours of the bell).
The gnomon was in form of a Cross having a hole of the diameter of a "scudo"
(a silver coin) at the intersection of the arms and was standing on an
hexagonal stone pedestal above a series of three steps.
The sundial does not exist any more. At present at its place there is a palm
tree .
The Prince Carafa himself designed both the plan of the village and the
sundial. In fact he was such an expert on sundialling to write a book on
this: "Exemplar horologjorum solarjum civilium" printed in 1692 by Van Berge
at Mazzarino (I'm still trying to trace out that book).
The to-day Community of Grammichele has now decided to restore the square
and has published a contest to that purpose. One of the candidates has asked
me to calculate the horizontal sundial to cover a large part of the
square.Thus the gnomon should be few meters high.
Obviously the sundial shall not be a reconstruction of the original one but
in order to maintain a certain continuity with the old one,I have been asked
to calculate also the point where the stylus would have cast its shadow at
the exact moment of the foundation of the village.
Thus 4 elements will be present in the new sundial: the hours of the usual
sundial for local time; the hours of the bell; the lemniscata for the 12
mean time; and the mark recalling the foundation of the village.
As presumably I have to document in writing my work I need the sun's
declination for that particular moment. Unfortunately the formulae reported
by the sources I have (Jean Meeus Astronomical formulae for calculators
1979) go back to 1900, but no further. And I cannot utilize an out-of-date
value for the sun declination.
This lack of knowledge has originated my request of help extended to the
subscribers of Sundial mailing list. And they have responded wonderfully.
Ciao
Angelo
Wall declination
Ciao to everyone! Many years ago I published in "Astronomia" N.2 Apr-June 1987 (ISSN: 0392-2308) p.14-17 a short review on the methods for measuring the declination of a wall. Most of them were taken from the literature. One was original, as far as I know, and is based on finding the time when the sun is in the plane perpendicular to the wall. Its technique is rather rough but easy and essential. A small mirror is fixed to the wall and a plumb-line is suspended in front of it at, say, 10 cm from the wall. Behind the line a sheet of paper is used to collect he reflected image of the sun. When the sun is in the plane perpendicular to the wall you will see on the paper two shadows of the plumb-line: one broader and more diffuse and another one narrower and more neat. The first one originates when the light hits the line before hitting the mirror and the second one when the light reflected by the mirror hits again the line. When the two shadows overlap the time is taken and the azimut is calculated therefrom. That's the declination of the wall. Instead of a plumb-line one can better use an element in form of a long vertical slit. For instance, a glass 70x3 cm on which two stipes of black adhesive tape are applied longitudinally spaced 1 mm from each other. In this case the sun light passes through the slit, is reflected by the mirror and again passes through the slit and finally is collected by the paper where two overlapping lights appears (instead of the shadows as above). The advantages of this method are that no geometric measure is required, but only time recording and that it is independent of atmospheric diffraction (other methods are). The disadwantages are that only one measure per day and at a precise time is possible and that it is applicable to walls not excessively declining. Due to the limited applicability in practice of this method I have not carried out extensive tests to determine its degree of precision. Ciao Angelo Brazzi --- 44 32' 10''N11 32' 15''E ---
Re: Definition of Time?
Bob, In the book "Tracce di Sole - Orologi Solari in Alto Adige" by Lucio Giudiceandrea and Rosina Ruatti, pag 191 Arunda (1989) is reported: "Il tempo è un trucco, con cui la natura evita che tutto succeda contemporaneamente" Graffito nel gabinetto dello Strictly Taboo Club a Dallas, Texas, firmato J.C. Translated into English: "Time is a trick. by which Nature avoids that all things happen contemporaneously" Graffiti in the toilette of the Strictly Taboo Club of Dallas, Texas, signed J.C. Ciao. Angelo At 09.56 15/10/98 -0700, Bob Haselby wrote: >Achim, My thoughts on time which I,m sure I read somewhere and I often >considered as a reasonable sundial inscription is: > "Without Time, everything would happen at once!" > >Thus the time keeps everything from happening at once. > >Bob Haselby [EMAIL PROTECTED] > > --- 44 32' 10''N11 32' 15''E ---
Measuring declination of a wall
Ciao a tutti! I would like to suggest a simple way to measure the declination of a wall. I fix a strip of mirror (say 3cm high 10 cm wide) horizontally to the wall by means of adhesive tape. Then I suspend vertically in front of it, and about 10 cm apart, a long strip of glass (say 20-30 cm high, 3cm wide) to which I have applied longitudinally two parallel strips of black adhesive tape in such a way to leave between them a slot of 2-3 mm. (all measures are indicative, experience can teach the best) When the sun is just in front of the wall the solar ray passing through the slot hits the mirror and the reflected ray passes through the slot again. I can realize that by collecting the reflected ray on a piece of paper. As the event takes a few seconds, I take the beginning and the ending times to calculate the mean time. From that time I can calculate the azimuth of the wall. Substantially I have converted an angle measure to a (hopefully) more precise measure of time. The method is simple, but it suffers from many disadvantages: you can take just one measure per day and just when the sun is in front of the wall (malicious clouds permitting), when the sun is very high in the sky you may need a very long strip of glass, which should be kept firmly strictly vertical. Ciao Angelo --- 44 32' 10''N11 32' 15''E ---
My new site WEB
Ciao a tutti! I'm pleased to announce that my Web site is opened at the address: http://web.tiscalinet.it/partena/index.htm May be it's poor and ruogh, but it's just to begin with. At the present it contains images of a few of my painted sundials. Ciao Angelo Brazzi
Fixing cilindrical gnomons
Ciao a tutti! I send you, herewith attached, an auto-expanding file containing a note on inconveniences which may arise when fixing a cilindical gnomon parallel to the earth axis, to a vertical plane, as well as the relating figures (a .jpg file). I would like to receive your comments both under the math point of view and about the practical usefulness of the conclusions of the note. Angelo Attachment converted: MAC Hard Disk:gnomon.exe (bina/mdos) (00017637)
Sun declination
I have to calculate a large orizzontal sundial (8-10 m stylus) and I need to know how to calculate, with a good accuracy, the sun declination for April 18 1693. The formulae reported by the sources that I have go back to 1900 but not further. Can anyone help me? Thanks. I found out about sundials mailing list from Sundials on the Internet. Angelo Brazzi
DOSBox and Dialist's Companion
It would be interesting to check whether the clock in the Excel spreadsheet "SUN" of RICARDO CERNIC (RNCERNIC at UOL.COM.BR.) keeps in agreement with the system clock. "SUN" is an Excel spreadsheet for Sun's ephemeris calculations and other important information for dialists. It works under MS XP and is available at the website "The Sundial Primer" - www.mysundial.ca. I cannot run the check because the OpenSource Spreadsheet I am using cannot open the protected macros of the application. Angelo Brazzi -- Angelo Brazzi angelo.bra...@tiscali.it http://web.tiscali.it/oldbones/index.htm No virus found in this outgoing message. Checked by AVG - www.avg.com Version: 8.5.339 / Virus Database: 270.12.56/2161 - Release Date: 06/07/09 17:53:00 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
