Re: Is This True?
WHAT?!? Elvis is *dead*??? No, It is not true. This is old news. I engaged in an interesting exchange of information with Alex Rawls and analyzed the tower as a gnomon for Islamic prayers, The whole data does not support the thesis. The Asr prayer line curves the other way. You have to invoke several complexities to achieve any kind of fit. I am satisfied that this is conspiracy theory, based on coincidence and a selective review of the data to support the premise. Add complexities when the facts deviate from the premise as in any classical conspiracy theory. I think this was discussed on the SML previously. I think I quoted Occam's Razor that the simplest explanation is likely correct. When competing hypotheses are equal in other respects, the principle recommends selection of the hypothesis that introduces the fewest assumptions and postulates the fewest entities while still sufficiently answering the question. That said, the architect showed arrogant insensitivity in choosing a red crescent as the dominant theme for his circle of red maple trees. Yes, the opening in the crescent does sort of point to Mecca. He says these are accidents of the geography of the crash site. Yes, the choice of a tower as the other highlight for the memorial is unfortunate as towers are used by Moslems as minarets for their call to prayer but also by Christians as bell towers. For Whom the Bell Tolls is a classic memorial. I give my heartfelt thanks to the rugby team members that said Let's roll, fought back and brought down the plane before its intended Washington target. It is unfortunate that the memorial site is diminished by this controversy, The architect was insensitive not considering the symbolism of the red crescent and a tower and the opponents are highly sensitive, over-interpreting the evidence. Remember that almost a majority of Americans believe the moon landings were fake, that Kennedy was killed by the Russians or a right wing cabal, that the twin towers were destroyed by Mossad and the CIA and Elvis lives. I remain a skeptical non-believer of these and other widely held beliefs. Regards Roger Bailey From: Richard Mallett Sent: Thursday, October 14, 2010 12:42 PM To: John Carmichael Cc: 'Sundial Mailing List' Subject: Re: Is This True? On 14/10/2010 17:17, John Carmichael wrote: Yesterday, I received an email from a fellow dialist containing the following link to an article written by some group called The Canada Free Press. He wanted to know if I could confirm its veracity. I've heard nothing about it. Have you? In the article it says this, among other things, about the Flight 93 Memorial presently being built in Shanksville Pennsylvania at the crash site: Another feature of paramount significance is a colossal 93-foot minaret-like tower that Rawls argues indicates time for prayer by functioning as an Islamic sundial. Do any of you know if anything in this article is true? See: http://canadafreepress.com/index.php/article/28649 --- https://lists.uni-koeln.de/mailman/listinfo/sundial This has been going round the Internet for months (years ?) - see a balanced account at :- http://en.wikipedia.org/wiki/Flight_93_National_Memorial -- -- Richard Mallett Eaton Bray, Dunstable South Beds. UK --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: DST Misconceptions
Even in Kunming, a much more culturally Chinese area, people liked to quote the time-honored maxim that the mountains are tall and the emperor is far away. I had to think of the line from Fiddler: Is there a proper blessing for the Czar? Yes, 'May God bless and keep the Czar --- far away from here!' --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: how Italian hours
Roger Bailey wrote: The conversion of the presentation to an article fro the compendium is stalled at 80% complete. This follows the classic 80 20 rule defining work progress. Which is to say that the remaining 20% of work will consume the *other* 80% of time? Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: New type of clock
All, A friend of mine (Joe Rao of New York City) just sent me this neat link. Check it out! -- Roger A different way to display time on the green time line. This is a real cool clock! I believe it comes from a Dutch web site. Yes! Some really cool things you can program in Flash... Did you try clicking on the sliderule clock? That brings you to a page full of interesting clock programs. Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Marton Géza's 2010 calendar
I have uploaded Marton Géza's magnificent sundial calendar to: http://www.twigsdigs.com/2010/calendar_2010.pdf Thank you, Bob! Merry Christmas Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Troublesome things these sundials!
The poor image attached might just be small enough to get transmitted but it certainly shows the extensive damage. Wow, looks like most STOP signs in the southern US, peppered with bullet holes... Some kinds of stupidity are universal, I guess. Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: BSS web site
The space-holder site seems to be safe, for what that's worth. I think Fabio hit it on the head, with the domain registration expiring. Looks like it was successfully re-registered, so once the DNS information is passed through the system, it should return to accessability. Unfortunately, the IP address in the WhoIs record ( 69.64.155.127 ) is still dead, leading to searchalligator, another fall-back page. Dave I tested the link http://www.sundialsoc.org.uk/ on both Mozilla Firefox and Internet Explorer after deleting the browsing history caches of both, and that stupid lawn website keeps coming up. Note that on that website, there is no way to contact the owners or the webmaster of that site! Note to Dave Bell: Hey Dave, since you know more about webmastering than most of us, could you look at this bogus website and see if there is anything odd about it (a virus maybe?). Could somebody have hijacked the BSS site? Who holds the domain name registration? -Original Message- From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Andrew James Sent: Wednesday, November 25, 2009 3:56 AM To: sund...@rrz.uni-koeln.de Subject: BSS web site Dear all I thought the British Sundial Society web site was at http://www.sundialsoc.org.uk/ - but it seems to have been hijacked to sell lawnmowers and such like! What is going on? Andrew James PRI Limited, PRI House, Moorside Road Winchester, Hampshire SO23 7RX United Kingdom Tel: +44 (0) 1962 840048 Fax: +44 (0) 1962 841046 www.pri.co.uk PRI Limited is a company registered in England and Wales with company number 2199653 Measure - Inform - Empower This correspondence is confidential and is solely for the intended recipient(s).If you are not the intended recipient, you must not use, disclose, copy, distribute or retain this message or any part of it. If you are not the intended recipient please delete this correspondence from your system and notify the sender immediately. This message has been scanned for viruses by MailControl. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Location aerial photography online
If I can't get a good result because the location is a new home in a new development, I go to bing.com and check it on their maps/aerials. They seem to have more recent aerial imagery much of the time. Jim Tallman Unrelated to dialing, but whereas I usually prefer Google maps and aerial and street views for general mapping needs, I *love* Bing for housing. A coworker is shopping for her first home, and we grizzled veterans have been kibitzing for her. Where Bing totally excels is their Bird's Eye view. The ability to swing around a location, viewing it from four cardinal directions and something like 30 degree elevation is fantastic! I'd love to know more about their software and image correcting process... Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Fwd: Direct reading time.
Use the best clock of all, the Sun (or Earth, if you prefer that new notion of Copernicus') - a photocell to track the Sun, advancing the mechanism one tick per day. Dave Bill All we need now is a good clock to control the mechanism which compensates for the EoT? Brian Albinson - Original Message - From: Bill Gottesman To: Robert Bargalló Cc: sundial@uni-koeln.de Sent: Sunday, September 27, 2009 10:24 AM Subject: Re: Fwd: Direct reading time. I like it. I would like to hear the story of how it was designed and fabricated. Is it located at a residence or a public place? -Bill Gottesman Burlington, VT Robert Bargalló wrote: -- Forwarded message -- From: Robert Bargalló bargallorob...@gmail.com Date: 2009/9/17 Subject: Direct reading time. To: Robert Bargalló bargallorob...@gmail.com Hello All, When an inexperienced person examine a well constructed Sundial, often underestimate the instrument because it is not marking the official time and having to make some antipathetic corrections of the indicated time. That is the main reason we have built a sundial that gives civil time accurately, enough to adjust the minute a non solar clock that it has stopped. In a word, in our quadrant needless resort to the equation of time or to the local position versus the Meridian corresponding to the time zone. No arithmetic corrections are needed. Descriptively, the device is a horizontal sundial with a gnomon consisting in thin thread nylon. The mechanism presents a 48 teeth gear, powered by an endless screw, which allows the entire clock to rotate some degrees around an axis parallel to the Earth rotation axis (around the gnomon). In other words, the mobile set plays like a hypothetical sundial indicating the exact civil time is elsewhere, in another position but in the same geographic parallel. As to the accuracy, the quadrant presents marks of all the minutes from the 5 h 45 a.m. until the 8 h 15 p.m. The single need featuring the device is that one or twice a week requires adjusts a rotatable knob to indicate the current date. This disc, of course, acts on the endless screw and, for that reason, on the rotation. Really, the rotation movement compensates not only the equation of the time, but also the error caused for the geographic longitude position of the instrument. For the same method we can use the sundial giving 3 types of time: the local solar time, the standard time, or the daylight savings. Since we installed it, from November 2006 to date, it has indicated time with an error that in no case exceeded one minute. Happy Dialling! Robert Bargalló More information at next blog --- https://lists.uni-koeln.de/mailman/listinfo/sundial -- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
[Fwd: RE: gnomon protection - shadow ridge dials]
Larry, I agree that waiting an hour (or 15 minutes, even) between brief illuminations would make it less usable. A couple of suggestions: A bunch of fiber strands spread across the bottom of each (larger diameter) well, converging into a single lighted spot. The brightest spot indicates the closest hour (or other interval), and an estimate can be made from the next-brightest. A graded filter, clear in the center, covering each well, with a single fiber in the center of the base. Works similarly to the above. Dave Rodney, Great illustration of what I call an incremental time dial (i.e., it only tells time at set increments throughout the day). About 20 years ago I had a dream of just such a hollow, thick skinned sphere (actually two spheres - one for each solstice to solstice period), but drilled with holes pointing to the sun's position (split analemmic pattern, one hole for each hour on the first, tenth, twentieth, thirtieth days of the month. Now envision each hole as a well and have fiber optic strand recessed inside the well such that the end of the strand is illuminated for just a short period that the sun is directly in line with the axis of the well. The fiber can be run to a display readout indexed for the date and time by which fiber is illuminated. While all of this might be technically possible, it strikes me that this a would be very expensive dial to make as well as being disappointing to users in having to wait for the sun to hit one of the wells in order to tell the time. The only solution to the latter is to create more holes and fiber strands and adding further to the cost of construction. I leave the idea to anyone who wants to pursue it. Larry Bohlayer -Original Message- From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On Behalf Of David Bell Sent: Sunday, September 06, 2009 2:42 PM To: Rodney Heil Cc: sundial@uni-koeln.de Subject: Re: gnomon protection - shadow ridge dials Very nice! I was thinking of it on a flat surface, with the tubes variously inclined, but this spherical model works great, too. Call it a Sea Urchin dial, maybe... Dave Sent from my iPhone On Sep 6, 2009, at 11:36 AM, Rodney Heil rodney.h...@gmail.com wrote: I made a quick POV-ray model of my conception of an anemone dial or porcupine dial and it is posted at www.flickr.com/photos/sundialstuff. Thanks to Roger for suggesting flickr. Respectfully, Rod ~35.5 N 117.5 W --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Inclining Cone Gnomons
Obviously, your insurers are well familiar with US litigiousness (and perhaps, incompetence!) Dave My insurers wanted $2,000,000 indemnity to cover the possibility of US clients falling onto a dial gnomon. They actually suggested building a wall around the dial to keep everyone at a safe distance! I solved the problem (to my satisfaction) by always having a 'halfpenny scroll tip' on my gnomons thereafter. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Electrical sundial tested
Excellent project, Aimo! I look forward to seeing this evolve. Dave As some of you already may have noticed, I have recently worked with my electrical sun dial project. Instead of a shadow the sun's position is in it calculated from the output of two or more solar panels. I have now tested the first prototype and found it capable for surprisingly accurate results, +-40 sec or even better, if the conditions are good. A description of the project is available at http://pc-calculator.110mb.com/sun/digital-sundial.html It has been really amazing to see how tiny movements of the sun the instrument capable to observe. Aimo Niemi --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Help with 'Analemmatic' - thanks to all, especially John Davis
It was interesting to see responses change, as time went on - from initially saying that it was simply not possible, to some 'lateral thinking' which could actually fulfill the design envisaged by our Mr Phillips Alison, that's the beauty of a group like this one, and something I've recognized many, many times, from the engineering mentality. All it takes is for someone (even one's self) to state that a task is impossible, to start the processes working to come up with creative solutions! Best of luck with Mr. Phillips. With John's help, I'm sure you can all come to an agreeable solution. Please let us know how it resolves, and send us photos of the dial! Dave Bell California --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Advice wanted, on 'Analemmatic' sundial orientation
Andrew James wrote: If, instead of standing on the central month scale, the user finds and stands on or near the hour number which casts his shadow onto the appropriate date, the numbers might be arranged to the South rather than to the North of the centre. This requires more action on the part of the user. Best practical suggestion I've seen yet! It would require making the date line markers visible from a distance, or possibly a daily (or weekly) placing of a small pylon by facility personnel. If the hours were not in a horizontal plane, perhaps they could be arranged to lie on a semicircle in some other plane - though not, I think, what Mr Phillips would like? Considering the relatively (to central US) high latitude, it might not be too extreme. Something like a ramped walkway (semi)encircling the area of the dial face. Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Advice wanted, on 'Analemmatic' sundial orientation
Good luck, Alison! I'll let the real experts address the weight of evidence, but you are quite correct, and Mr. Phillips is wrong. While many types of sundials can indeed be adjusted to operate in any location, they cannot be adjusted to arbitrary orientation. For the simplest argument you might present to him, point out that the human gnomon casts a shadow to the North (at say, local noon). It would be impossible to place the hour lines/points to the South and have them function! (He isn't from Australia, by any chance?) Dave Dear Sundial Experts, I have recently joined this Mailing List, and hope that any members will be able to give me some assistance on the following situation. Our local Stately Home (Kentwell Hall, Long Melford, Suffolk) is considering installing an Analemmatic sundial, as a new interactive attraction for visitors - but we are getting 'conflicting' advice, on whether this 'Human Sundial' will work in the way we want it to. We have been in discussion with Modern Sunclocks (apparently the acknowledged 'experts' for these features), who have told us that its central scale of dates must be aligned North/South - plus that hour markers must be correctly positioned on an elliptical ring, and which would lie on the Northern side of that scale of dates. Photographs on their website ( www.sunclocks.com ) confirm this. However, our 'Director of Operations' (Mr Phillips) absolutely INSISTS that he wants the scale to run exactly parallel with our main driveway - on a compass bearing which is about 162 degrees from North, with the hour points placed on its Southern side. He also wants the hour points to form an exact semi-circle, and not be elliptical in shape. Mr Phillips refuses to accept that he cannot arbitrarily position the Human Sundial feature as he wishes, and says that it must be possible to create this so that it could then align with the existing layout of buildings/paths. Can anyone on this Mailing List tell me whether it is possible to install a Human Sundial to fit any existing orientations, (with appropriate re-calculation of its component parts) - or, if not, just confirm that it must be as Modern Sunclocks have told me. I can then show the 'weight of evidence' to Mr Phillips. Because Kentwell Hall is a well-known Stately Home (open to the public), we should not want to become a 'laughing stock' by installing a feature which does not work - despite Mr Phillips assurance that all types of sundial can be adjusted to work, in any location. Looking forward to all comments (to this List, or sent privately). Sincerely, Alison Shields. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: A Most Beautiful Dial!
Also curious, I don't recall any mention of the two auxiliary dials, with the cherubim holding their own styles, one 4 hours fast, the other 4 hours slow relative to the main dial. And what about the apparent four additional styles, one at each lower corner of the window frames? Dave Dear John, Thank you for bringing this to our attention! The Wilanow Palace sundial photo and its description can also be found at: http://en.wikipedia.org/wiki/Image:Warsaw_Wilanow_Palace_sundial.jpg This is indeed an interesting sundial, but also an interesting photo. Karl Schwarzingers photo led him to state that Chronos holds style with a pierced gnomon shaped as sun, and indeed it looks that way in his photo. The hi-res one clearly shows that the supposed pierced gnomon actually is a sun face stuck to the wall. So the date is read at the tip of the rod, which fits in with the date the photo was taken: June 25. In addition, the rod is not a pole style, which is clear from the fact that its shadow does not line up with the hour lines. Best regards, Frans John Carmichael wrote: Recently I came across a website that has a high definition photo of what I think is one of the worlds most beautiful sundials. It is a sundial made of sculpted painted plaster or stone (I cant tell which), and its located on a wall of The Royal Palace of Wilanow in Warsaw Poland. (Actually, its a multiple dial with three separate faces). I have known about this dial for years now from Karl Schwartzingers website. But Karls photo was not of high quality and I never was able to find a high resolution photo of it until now. If you have a slow modem, Its worth the wait to see it in high definition. High Definition Photo (2 MBs) : http://upload.wikimedia.org/wikipedia/commons/b/b1/Warsaw_Wilanow_Palace_sundial.jpg You must also see the closeup photos of it at this website (click on the word dalej under the photo): http://www.wilanow-palac.art.pl/index.php?id=195 Here are the other photos of it on Karls site: http://members.aon.at/sundials/bild33_e.htm Enjoy! John Carmichael* * *Dial 31* *Delineator: *John Hevelius, astronomer of Gdansk and Adam Adamandy Kochanski, royal librarian and mathematicians *Painter: *unknown *Location: *Poland, Warsaw, The Royal Palace of Wilanow *Date: *1681-1682, Restored 1995 *Photo Origin: *Photo a was taken by Arnold Paul on 06-25-2006 and is copied from Wikimedia.org website below. Photo b is by Karl Schwarzinger and was sent to us by him. *Photo Permission: *Photo a is used following terms of the license below. Photo b is used with permission from Karl Schwarzinger. Please do not copy photo a without using the license available online. Please do not copy photo b without permission from Karl Schwarzinger. *Karl Schwartzingers Website: *http://members.aon.at/sundials/bild33_e.htm *Website: *http://www.wilanow-palac.art.pl/index.php?id=195 *Website: *http://commons.wikimedia.org/wiki/Image:Warsaw_Wilanow_Palace_sundial.jpg *Creative Commons License: *http://creativecommons.org/licenses/by-sa/2.5/ http://advanceassociates.com/WallDial/Pinkies/PWS_031a.jpg http://advanceassociates.com/WallDial/Dials/PWS_031a.jpghttp://advanceassociates.com/WallDial/Pinkies/PWS_031b.jpg http://advanceassociates.com/WallDial/Dials/PWS_031b.jpg --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Astronomical Clocks
I just ran across this photoset today. Along the same lines as the Prague clock, and reminds me of Jim's beautiful astrolabes... http://www.flickr.com/photos/seangallagher/sets/72157604323095889/detail/ or http://tinyurl.com/5fjs3q Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Dali sundial +
Some time ago someone posted a link to a painting by Salvador Dali that included a sundial. Could someone point me to it again? I found this: http://peregrinations.kenyon.edu/vol1-3/gower.pdf == Try this: == Since it has none, I suppose a sundial could be considered the timepiece with the least moving parts. What timepiece has the most moving parts? Why, an hour glass, of course! Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Monumental sundial
As you probably know, Britain (and England in particular) is filled with such memories of the past and we tend to take them for granted until others mention them!. I find the same here, except our past is so recent, compared to yours! Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Monumental Sundial
Very intriguing idea, Edley! Should be great fun experimenting. I'm going to look for some trial ray-tracing software... Dave Some time ago an idea for a nodus on a Large Sundial appeared to me. It is the shadow of a thin-walled transparent sphere. This can be seen simply in the shadows of soap bubbles and transparent round helium balloons. This is not considering it a lens, just the shadow cast. As a lens, such a structure is a diverging lens, but the shadow has a bright spot when the distance is proper for it's size. The central light bundle is little refracted and outer bundles are reflected at Brewster's or other angles, leaving a surrounding shadow. It appears much like the shadow of a disk with a hole in it, but works the same with light from all directions. At a proper, and quite large distance, the central aperture acts much like a pinhole. I've not tried large spheres, but possibly those of glass or plastic, especially coloured transparent materials would give a distinctive small bright spot surrounded by shadow. I've no idea how to calculate the proper dimensions, size, wall thickness, surface shinyness, etc. But, it could work very well at hundreds of feet away. If someone figures out how to calculate this effect, I'd be pleased to hear about it. Thanks! Edley McKnight PS. John, I decided to let the list know. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Cute ad-hoc dial at AutoDesk Labs
World's cheapest sundial: http://labs.blogs.com/its_alive_in_the_lab/2007/09/our-autodesk-la.html Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Dialist for PDA
Simon wrote: Of course, if you had C, C++, FORTRAN, LISP, COBOL, JAVA, Python, Scilab, Euler, Pascal, Basic, etc on your PDA, then you might look at my web site. I added the Python, Scilab, and Euler code for dial design just this week. What?!? No SNOBOL? On the other hand, Forth would actually be very reasonable for a small platform like a PDA. Of course nowadays, you'd have to implement the kernel in Java! Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: bone terrestrial globe with sundial
I happen to own a small version of this exact item. I must concur with Sara that it is not what it purports to be. I picked up the small (about 5 high) version a few years ago as a curiosity - lamenting all the time that the gnomon design and placement make the whole thing useless. This is almost definitely a modern attempt (made in several different sizes!) to put one over on emptores who ignore the caveat! Fred Sawyer Especially from Fred's experience with seeing similar dials, I agree with its lack of authenticity. My only thought about the gnomon design on first seeing the eBay photos was that the globe/dial might be designed with a tilted or even adjustable polar angle, like most modern globes. Wouldn't that make the dial a polar design, and the perpendicular style edge correct? Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Old dial design article
Interesting article from a 1949 Mechanix Illustrated... http://tinyurl.com/37ff9x Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Direct South Dial
While Willy is absolutely correct, the part about knowing and computing
for the shape of the dish is probably the real killer task.
This is an application where I would advocate the empirical approach:
Properly orient the dial face and style, then manually lay out points,
with a watch in hand. Plan ahead and (weather cooperating) do it on the
Equinox, and you can draw lines through the points to the dial center, at
the root of the style.
Dave
Hi Andrew,
you have to orient the disc to the south
you have to decline the disc to a vertical position
on a vertical and south oriented plane behind the disc you have to
work out (virtually) the hour lines and date lines of a vertical
south oriented nodal sundial - the node must be a part of the style
of your sundial
the lines from the node to 'specified points' of the plane sundial
intersects the disc at the equivalent points on the disc ('specidied
points' are the intersection points of the hour lines and date lines)
to do this mathematically the shape of the disc must be known; is it
a globe, a paraboloid, a hyperboloid ...?
Willy Leenders
Hasselt in Flanders (Belgium)
Op 21-jun-07, om 19:27 heeft Andrew Corl het volgende geschreven:
Greetings all,
Several months ago I bought a house and the previous owners left me
with one of those 12 diameter satellite dishes. I have no need or
want of Direct TV or satellite TV.
I was sitting there thinking one day that it would make a really
nice direct south facing sundial. My house already faces a little
east of south anyway, and the location where the dish is gets
direct sunlight almost all year round.
My questions is this: Do I need to make any adjustment in the
calculations of the hour lines for the shape of the dish? If so
what is the formula?
I am going to install a simple style using a metal road about a
half inch in diameter. I want this sundial to tell solar time not
necessarily actual time. Though one day I may install an equation
of time underneat the dial .
Boardwalk for $500? In 2007? Ha!
Play Monopoly Here and Now (it's updated for today's economy) at
Yahoo! Games.
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RE: Equation of Time
Concerning equatorial tables, people seem to be looking at recent patents for ELABORATE designs (conical rollers and such). But the original Poncet table is quite simple. I made my 1977 prototype out of wood, with a piece of Formica for the inclined plane on which one end of the table slides. My unit has no curved surfaces at all. I agree - all I see lately are roller bearing designs, not the sliding plane. Smooth, frictionless motion is NOT needed here! I took it to Turkey for the 1999 eclipse (latitude 39 N) We went to Romania for 1999... Did you get out before the quake? Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Russell Porter sundial
The Patent for Porter's reflecting telescope is available directly from the patent office's online site at a huge long url, which is too long to type in or put on a single line. For future reference, there's an easy fix for that problem: Once you have navigated to the site with the long URL, copy it from the address bar, then go to http://tinyurl.com Enter the long url, hit Make a shorter URL, and copy the tiny result to paste into your email. They keep just the link association you create, but keep it forever. And it's totally free... You can just go to: http://patft.uspto.gov/netahtml/PTO/search-bool.html and search for telescope in title and porter in inventor, yielding two patents, one for the refracting, and one for the reflecting one.(having set the full database period in the selection ) Another very useful free site is http://pat2pdf.org Enter the patent number, and they will retrieve the TIFF images and create a multi-page pdf file you can download or view immediately. No TIFF plugin required! Dave --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Analemmatic dial
Malcolm McClure responded to M. Jacquelin Hardy's questions about building an anlemmatic dial: I am still thinking about this one, but hope the following suggestions will help. (Corrections to logic gratefully received) I have seen a photo of a wall mounted analemmatic sundial at Greenwich. It has a fixed perpendicular rod about a meter long at the top, with a sun-shaped cutout piece of metal welded on the end. This disc has a central hole about a centimeter in diameter, which acts as the style. The analemma is painted on the south-facing wall beneath, such that the top The logic is fine, as far as I could tell, Malcolm, but I think you're describing a different type of dial. The vertical dial you outlined seems to be equivalent to a conventional dial, with the hour lines drawn as analemmas (..ae?), to correct for declination and EoTime. The one Hardy is asking about is quite unconventional, compared to a horizontal dial, or it's vertical cousins. This type of dial, if you look down on it from above, is layed out as roughly half of an ellipse, with the major axis running East-West, and the half-minor axis pointing North (in the N hemisphere!). The gnomon is not parallel to the Earth's axis, but is a vertical pole placed on the N-S center line, and moved N and S a small amount each day. The pointer is the shadow of the top of the gnomon, and falls on the elliptical perimeter to mark the hours. In large garden or monumental versions, the gnomon is often designed to be the user, who stands on date markers. I don't have any references here at work, but I believe Waugh did a good workup on this design. I'll see what I can find, this evening. Dave [EMAIL PROTECTED] [EMAIL PROTECTED] (M. Jacquelin Hardy) wrote I am looking for info. on how to build an analemmatic sundial ( we call them cadran analemmatique in french). There are a few of these in Europe, (near the church of Brou in Bourg-en-Bresse, France) is one of them. The dial is horizontal and the gnomon is vertical and moved along the North-South axis during the year. This movement is my problem: I read in a book that d( movement of the gnomon) is equal to tg (Decl. of sun)/cos (lat.) For example, on June 21st in lat. 45N , the gnomom should be moved tg 23.45/cos 45 , ie. approx. .42/.7 or .6 times diam./2 along then N-S axis to give the time correctly. It doesn't seem to work right according to my calculations. Please help!
