Re: date scale
Tracy Paine wrote: Thanks Frans for your info! If I understand you correctly, you are saying that the analemma is positioned along the E-W line? Horizontal instead of vertical? The vertical line in the figure is the regular date line, which is on the N-S line (minor axis) of the ellipse. The short horizontal line is the EoT scale, which thus falls on the E-W line (major axis). I have added the scale values in the attached figure. Locate the date on the analemma curve and read the EoT correction from this scale. If the EoT is positive (to the right of the date line), add the correction to the time read, if negative, subtract. Here, the date is indicated by the zodiac signs alongside the analemma, as well as by the calendar months (in Roman numbers) along the date line. In practice, this could be simplified a bit. Regards, Frans --- https://lists.uni-koeln.de/mailman/listinfo/sundial
date scale
Hi Everyone My date scale has been put on hold for a little bit since it is so cold now: 12 degrees F at night and only in the 30's during the day! B! I hope this cold weather doesn't hurt the concrete - it was pretty hard before the cold front came in. It was 60 degrees the day the concrete was poured! Thanks Frans for your info! If I understand you correctly, you are saying that the analemma is positioned along the E-W line? Horizontal instead of vertical? Jim - thanks for the picture of your cats! They are so great! The black one looks like one of our cats "Planet". I love your sundials! I have seen your website before when I was scanning the internet - I think I put it in "my favorites" lol! The site itself is superb! I have fishtanks in my house and sometimes the light shining through the window hits the tanks just right and behold a rainbow on the wall! I love it! Thanks Chris for your info. A round date scale...hmm. I was noticing when comparing the date scale to the analemma that the months did go around the centerline in a circle. I like the circle format. Thank you John for answering my questions. Thanks for the copies of the date scales and the picture. Is that you in the middle? Tony - thanks for the powerpoint presentation on the analemma! That is great! Your heliochronometer is very cool! Thanks Fer de Vires for you info! More info on my dial: The large basalt rocks I used for the hour marks were laying along the fenceline of our cow pasture (an abandoned rail road bed). They were taken out of the ground when the drainage ditch was dug way back when for the railroad track. There's a lot of basalt in Washington from old volcano flows. Some of our rocks must be over 300 pounds. My friend and I moved them by wrapping a heavy chain around them and pulling with a pickup truck. Then rolling them onto a metal "sled". Then we pulled the sled with the truck to the sundial and manouvered them into place. Of course I had to have them PERFECT so this took a while! The rest of the concrete: I ordered 4 yards of concrete - some of it for the dial, but most of it for another project I am working on: converting the chicken pen into an art studio! The chickens already have their new pen - this time far away from my house - boy they are noisy! And now the floor is in for the studio. YEA! Now I will be insulating the walls, wiring, etc. I learned how to do all this stuff from my husband. It's fun! I am always doing projects. I love to use my hands and be outdoors. I plan on making a labyrinth someday. I am also working on a "trail" that will wind around the perimeter of our property. I plan to make a suspention bridge along part of the trail that will cross the abandoned rail road bed where there are basalt cliffs on either side. So many projectsso little time! (maybe this should be my dial motto!Ha ha!) Tracy --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: date scale
Hello Tracy, Sorry for jumping in so late. You like to have an analemma associated with the date line? There is a nice way, introduced by Marinus Hagen, founding father of the Dutch Sundial Society. See the small attached figure. One should stand right on the date line, as explained before. The analemma has a scale along the E-W axis, from which the EoT correction can be read. The large ticks are at 5 minute intervals. This is in fact an alternative for the use of a table or a separate EoT graph. Best regards, Frans Maes - Original Message - From: "Tracy Paine" <[EMAIL PROTECTED]> To: "sundial list" Sent: Sunday, October 29, 2006 10:52 PM Subject: date scale Hello Everyone I really like the drawing you made John for your customers - it helps a lot. Thank you. Thanks Tony for the picts and Powerpoint presentation - it is wonderful. Thanks Chi-Lian and Linda for your comments. After reading the advice I have received, I think that I will make my date scale the conventional way - although I think the analemma looks way cooler! It looks as if the first day of summer and the first day of winter are at each end of the scale. Is this true always? Also, does one stand directly on the centerline, or on the month "block" which falls to the left and right of the center line? More on my previous obsession of using the figure 8 in the date scale: If I am not mistaken, an analemma, on the ground for instance, can be made by marking the position of the sun (cast by some point) at the same time for a year every few days or so. I am referring to the website: http://www.cerrilloshills.org/analemma/path3.htm So, if I were to mark the path at noon, local time, for a year, the figure 8 should fall on the N-S line? It appears as though the months outlined on the figure 8 match the date scale in placement except at the top portion of the figure 8 where the months seem to flip from the left side to the right side. I can't help but think that the straight line date scale mimics the analemma in month placement. That's why I figured that I would make the figure 8 instead of the plane straight line. Also, I thought about positioning some type of gnomon that would cast a bright spot (or shadow) on the date scale which could follow the figure 8 path exactly (at noon) just like the noon analemma sundial featured in the website above. I am fascinated by the analemma and would love to somehow use it in my sundial, however, I definitely want my sundial to be correct and accurate - no false sundials here! But I keep seeing the analemma used as a date scale in pictures on the internet. One I found looks like it is bronze. If I shouldn't use the analemma in the date scale, where could I put it in the sundial properly? Or, should I just make a separate noon analemma sundial like that in the website referred above? > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > hagen-analemma.gif Description: GIF image --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: date scale
Hi Tracy, I've attached a photo of the date scale I did for an analemmatic sundial at a swimming pool. The footprints are intended to hint that you should stand on the centreline. The date scale is a circle. Find the date on the circle, mentally follow the east-west line to the inner arc, then follow a radial line to the centreline. Stand there. The entire sundial, including this diagram, was drawn without a ruler, and with no calculations, except for one tiny detail. You need only an east-west line, a protractor and a length of string! The month names were painted by children, hence the delightful hand-made feel. This doesn't give you the analemma, but it does graphically show how the place you stand relates to the date. The date scale divides the circle in 365.25 daily arcs (28 Feb has 1.25 of them) with the solstices on the N-S line. The one tiny detail for which you need a calculation is the very small offset from the centre of the date circle to the point from which you measure those daily arcs. It needs to be offset to compensate for the eccentricity of the earth's orbit. If done correctly, this places the autumnal equinox on September 23rd, not 21st as it would be if the orbit were circular. But this correction is so small you may ignore it in practice if you wish. I thought I'd invented this construction (it isn't in Cousins or any of the other common sundial books) but have found that it has been known for centuries! Chris Lusby Taylor 51.4N 1.3W - Original Message - From: Tracy Paine To: sundial list Sent: Sunday, October 29, 2006 9:52 PM Subject: date scale Hello Everyone I really like the drawing you made John for your customers - it helps a lot. Thank you. Thanks Tony for the picts and Powerpoint presentation - it is wonderful. Thanks Chi-Lian and Linda for your comments. After reading the advice I have received, I think that I will make my date scale the conventional way - although I think the analemma looks way cooler! It looks as if the first day of summer and the first day of winter are at each end of the scale. Is this true always? Also, does one stand directly on the centerline, or on the month "block" which falls to the left and right of the center line? More on my previous obsession of using the figure 8 in the date scale: If I am not mistaken, an analemma, on the ground for instance, can be made by marking the position of the sun (cast by some point) at the same time for a year every few days or so. I am referring to the website: http://www.cerrilloshills.org/analemma/path3.htm So, if I were to mark the path at noon, local time, for a year, the figure 8 should fall on the N-S line? It appears as though the months outlined on the figure 8 match the date scale in placement except at the top portion of the figure 8 where the months seem to flip from the left side to the right side. I can't help but think that the straight line date scale mimics the analemma in month placement. That's why I figured that I would make the figure 8 instead of the plane straight line. Also, I thought about positioning some type of gnomon that would cast a bright spot (or shadow) on the date scale which could follow the figure 8 path exactly (at noon) just like the noon analemma sundial featured in the website above. I am fascinated by the analemma and would love to somehow use it in my sundial, however, I definitely want my sundial to be correct and accurate - no false sundials here! But I keep seeing the analemma used as a date scale in pictures on the internet. One I found looks like it is bronze. If I shouldn't use the analemma in the date scale, where could I put it in the sundial properly? Or, should I just make a separate noon analemma sundial like that in the website referred above? ---https://lists.uni-koeln.de/mailman/listinfo/sundial <> --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: date scale
Hello Tracy, For an usual analemmatic dial an analemma around the central scale of date is not suitable for correcting the time with the value for equation of time if it isn't noon. For other times the analemma is just a table to read the value of the EoT. For such a reason you may draw the analemma of course but don´t use it for correct time reading, except at noon. But there are possibilities to have an analemma on your dial that will work, however it is an approximation. Split the dial into a morning half and an afternoon half. Each part get´s its own analemma. So you have a dial with two analemma´s. Such dial may be calculated with a program by Helmut Sonderegger, Austria. An example is attached. You see that the shape of the analemma´s is a liitle changed but still they are analemma´s. There is a small error in the readng but for sundial it is still a good reading you get. Best wishes, Fer. Fer J. de Vries De Zonnewijzerkringmailto:[EMAIL PROTECTED]http://www.de-zonnewijzerkring.nl Eindhoven, Netherlandslat. 51:30 N long. 5:30 E - Original Message - From: Tracy Paine To: sundial list Sent: Sunday, October 29, 2006 10:52 PM Subject: date scale Hello Everyone I really like the drawing you made John for your customers - it helps a lot. Thank you. Thanks Tony for the picts and Powerpoint presentation - it is wonderful. Thanks Chi-Lian and Linda for your comments. After reading the advice I have received, I think that I will make my date scale the conventional way - although I think the analemma looks way cooler! It looks as if the first day of summer and the first day of winter are at each end of the scale. Is this true always? Also, does one stand directly on the centerline, or on the month "block" which falls to the left and right of the center line? More on my previous obsession of using the figure 8 in the date scale: If I am not mistaken, an analemma, on the ground for instance, can be made by marking the position of the sun (cast by some point) at the same time for a year every few days or so. I am referring to the website: http://www.cerrilloshills.org/analemma/path3.htm So, if I were to mark the path at noon, local time, for a year, the figure 8 should fall on the N-S line? It appears as though the months outlined on the figure 8 match the date scale in placement except at the top portion of the figure 8 where the months seem to flip from the left side to the right side. I can't help but think that the straight line date scale mimics the analemma in month placement. That's why I figured that I would make the figure 8 instead of the plane straight line. Also, I thought about positioning some type of gnomon that would cast a bright spot (or shadow) on the date scale which could follow the figure 8 path exactly (at noon) just like the noon analemma sundial featured in the website above. I am fascinated by the analemma and would love to somehow use it in my sundial, however, I definitely want my sundial to be correct and accurate - no false sundials here! But I keep seeing the analemma used as a date scale in pictures on the internet. One I found looks like it is bronze. If I shouldn't use the analemma in the date scale, where could I put it in the sundial properly? Or, should I just make a separate noon analemma sundial like that in the website referred above? ---https://lists.uni-koeln.de/mailman/listinfo/sundial Image1.gif Description: GIF image --- https://lists.uni-koeln.de/mailman/listinfo/sundial
[karl: Re: date scale]
Lets try again with my subscribed address... Karl - Forwarded message from karl - Subject: Re: date scale Date: Fri, 27 Oct 2006 22:34:36 +1000 Message-ID: <[EMAIL PROTECTED]> To: sundial@uni-koeln.de On Fri, Oct 27, 2006 at 10:53:53AM +0100, Chris Lusby Taylor wrote: > Hi Tracy, You say " I may make lines that radiate from the center out to the > hour marks anyway." Please don't. > > The hour marks are on the ellipse. The shadow falling on, say, the 10 > o'clock mark comes from a different direction depending on the time of year. > By standing on the correct date mark, you compensate for that. But radiating > lines have to radiate from somewhere, and that somewhere would be wrong > except on a couple of dates. Radiating lines would not help read the time > accurately, in fact they would mislead. I recently came across an interesting interactive sundial (Argyle Sq., Carlton, Melbourne, Australia). It is a horizontal sundial. The scale along the N/S line is height rather than date. By standing on the appropriate spot, the top of your head is the along the gnomon style so where your shadow ends is the time. In this case, lines radiating from the dial centre are necessary. Karl - End forwarded message - --- https://lists.uni-koeln.de/mailman/listinfo/sundial
date scale
Hello Everyone I really like the drawing you made John for your customers - it helps a lot. Thank you. Thanks Tony for the picts and Powerpoint presentation - it is wonderful. Thanks Chi-Lian and Linda for your comments. After reading the advice I have received, I think that I will make my date scale the conventional way - although I think the analemma looks way cooler! It looks as if the first day of summer and the first day of winter are at each end of the scale. Is this true always? Also, does one stand directly on the centerline, or on the month "block" which falls to the left and right of the center line? More on my previous obsession of using the figure 8 in the date scale: If I am not mistaken, an analemma, on the ground for instance, can be made by marking the position of the sun (cast by some point) at the same time for a year every few days or so. I am referring to the website: http://www.cerrilloshills.org/analemma/path3.htm So, if I were to mark the path at noon, local time, for a year, the figure 8 should fall on the N-S line? It appears as though the months outlined on the figure 8 match the date scale in placement except at the top portion of the figure 8 where the months seem to flip from the left side to the right side. I can't help but think that the straight line date scale mimics the analemma in month placement. That's why I figured that I would make the figure 8 instead of the plane straight line. Also, I thought about positioning some type of gnomon that would cast a bright spot (or shadow) on the date scale which could follow the figure 8 path exactly (at noon) just like the noon analemma sundial featured in the website above. I am fascinated by the analemma and would love to somehow use it in my sundial, however, I definitely want my sundial to be correct and accurate - no false sundials here! But I keep seeing the analemma used as a date scale in pictures on the internet. One I found looks like it is bronze. If I shouldn't use the analemma in the date scale, where could I put it in the sundial properly? Or, should I just make a separate noon analemma sundial like that in the website referred above? --- https://lists.uni-koeln.de/mailman/listinfo/sundial
date scale
Hello Everyone! I will definitely send picts of my sundial out to those that want it, however, it is still a work in progress - I can send more when it's completed. I tried again to send them here, but the files are just too big. Thanks Chris for pointing out to me that I can't make the radiating lines - of course not, what was I thinking? Ha ha! I like the mosaic sundial on that website. What is wrong with the analemma? That is how I want my date scale to look. Thank you Tony for the info I will check it out. That is a great sundial - is that you laying it out? Did you build it? A little about my sundial: the tops of the basalt rocks (hour marks) are all flat and I leveled them (the best I could) - my cats enjoy jumping up on the rocks and basking in the sun. They also like to jump from rock to rock all the way around the ellipse as I walk around with them! They just love the sundial. There's a special energy you can feel when you are in the sundial. I think they feel it too! I positioned a sitting rock (it's shaped like a seat kind of - fits a bum perfectly!) on the N-S line near the 'bottom' of the sundial so one can just sit there and be happy. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: date scale
Hi Tracy & Others: While researching mosaic dials I recently came across this beautiful but severely flawed analemmatic sundial in Sabadell Spain. Notice that it incorrectly has an analemma instead of a date line. Also, it is enormous measuring 12 x 8 meters. The user’s shadow is way too short to reach the hour markers. This otherwise beautiful mosaic dial must have cost a lot of money to build so it really is unfortunate that these common design errors continue to be made in new analemmatic sundials. Even more surprising and disturbing is that it was designed by the Vice President of the Catalonia Sundial Society. See this website: members.aon.at/sundials/bild36e.htm John Carmichael Hello Tracy, Chris provides some good advice. The center line on the N/S axis is correct. The noon hour point offset we assume is the longitude correction. This shifts all the hour points accordingly. Your size, 33 ft major axis is fairly large. Appropriate for your design perhaps but be aware of the short shadow lengths in the summer for a person as the gnomon. Also be aware that the normal analemma shape provides a time correction E/W only. This works for noon but for the corrections in the N/S direction for other hours, AM and PM go in opposite directions. Two analemmas and a split dial can provide better correction but generally this is not worth the effort. From your relatively local "palouse.net" email address I wonder if you may have seen the Skaha Lake analemmatic sundial near Penticton BC. It is billed as the "Worlds Largest Analemmatic Sundial". In my opinion it is too large and falls into the "analemma correction for an analemmatic sundial" trap. But it is a great point of local interest on the beach. Have you considered seasonal markers that use the dial to tell when and where the sun rises and sets throughout the year. I consider these to be a simple and useful additional feature for analemmatic sundials . Ok, I am biased but... There is some useful information on such things as shadow lengths and seasonal markers on my fairly primitive personal website http://www3.telus.net/public/rtbailey/ Regards, Roger Bailey Walking Shadow Designs N 48.6 W 123.4 Sidney by the Sea, BC -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]On Behalf Of Tracy Paine Sent: October 26, 2006 5:55 PM To: sundial@uni-koeln.de Subject: date scale Hello Thank you Chris. In regards to your question, the major axis of my sundial is 33 feet. I used large basalt rocks for the hour marks. I tried to send a picture of it here, but the file was too big I guess. I plan to mosaic the top of the concrete date scale after it is cured. I would like to depict the analemma itself, colored according to the seasons with the months marked around it. Tracy --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: date scale
Hi Tracy, You say " I may make lines that radiate from the center out to the hour marks anyway." Please don't. The hour marks are on the ellipse. The shadow falling on, say, the 10 o'clock mark comes from a different direction depending on the time of year. By standing on the correct date mark, you compensate for that. But radiating lines have to radiate from somewhere, and that somewhere would be wrong except on a couple of dates. Radiating lines would not help read the time accurately, in fact they would mislead. That's why I asked how big the dial was. For a given latitude, the size of the dial is fixed once you've decided on the length of the date scale (or vice versa). A ten foot long date scale inevitably needs a big dial. I find a three foot date scale quite long enough in England. A lot of people seem to think you must stand facing north on an analemmatic sundial. In fact, it's better to stand with your back to the sun, as your shadow will be more symmetrical and it is also easier to look up, mentally extending your shadow out to the dial ellipse, or to hold both arms up to make your shadow longer. Best wishes Chris - Original Message - From: Tracy Paine To: sundial@uni-koeln.de Sent: Friday, October 27, 2006 6:52 AM Subject: Re: date scale Hi Roger Thanks for the info. I have HUGE rocks for the summer, spring/fall, and winter sunrises that lie just outside the sundial ellipse. However, after reading through the seasonal markers section of your website I now realize what the seasonal markers are. I placed the rocks so that the "line" from the sundial to the horizon, where the sun rises, passes through the center of the sundial! Oops! I am beginning to see now why this type of sundial is in an elliptical shape - I never fully understood that. I also have the seasonal sunrises marked further out on our property as well as the N-S and E-W lines. But they all line up with the center of the sundial. I am definitely going to add the "real" seasonal markers to the sundial. I have been working on this sundial project for quite sometime. I started a long time ago, and kept moving the location using portable hour marks. My shadow in the summer just about reaches the hour marks. I may make lines that radiate from the center out to the hour marks anyway. I really enjoy making this sundial. It is fascinating to me. I love learning new things about these sundials - some of it is over my head though and takes time to figure out. I appreciate you all and the great information I have been getting. Thank you again. Tracy p.s. I have not seen the Shaha Lake analemmatic sundialyet. ---https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: date scale
Hi Roger Thanks for the info. I have HUGE rocks for the summer, spring/fall, and winter sunrises that lie just outside the sundial ellipse. However, after reading through the seasonal markers section of your website I now realize what the seasonal markers are. I placed the rocks so that the "line" from the sundial to the horizon, where the sun rises, passes through the center of the sundial! Oops! I am beginning to see now why this type of sundial is in an elliptical shape - I never fully understood that. I also have the seasonal sunrises marked further out on our property as well as the N-S and E-W lines. But they all line up with the center of the sundial. I am definitely going to add the "real" seasonal markers to the sundial. I have been working on this sundial project for quite sometime. I started a long time ago, and kept moving the location using portable hour marks. My shadow in the summer just about reaches the hour marks. I may make lines that radiate from the center out to the hour marks anyway. I really enjoy making this sundial. It is fascinating to me. I love learning new things about these sundials - some of it is over my head though and takes time to figure out. I appreciate you all and the great information I have been getting. Thank you again. Tracy p.s. I have not seen the Shaha Lake analemmatic sundialyet. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: date scale
Hello Tracy, Chris provides some good advice. The center line on the N/S axis is correct. The noon hour point offset we assume is the longitude correction. This shifts all the hour points accordingly. Your size, 33 ft major axis is fairly large. Appropriate for your design perhaps but be aware of the short shadow lengths in the summer for a person as the gnomon. Also be aware that the normal analemma shape provides a time correction E/W only. This works for noon but for the corrections in the N/S direction for other hours, AM and PM go in opposite directions. Two analemmas and a split dial can provide better correction but generally this is not worth the effort. From your relatively local "palouse.net" email address I wonder if you may have seen the Skaha Lake analemmatic sundial near Penticton BC. It is billed as the "Worlds Largest Analemmatic Sundial". In my opinion it is too large and falls into the "analemma correction for an analemmatic sundial" trap. But it is a great point of local interest on the beach. Have you considered seasonal markers that use the dial to tell when and where the sun rises and sets throughout the year. I consider these to be a simple and useful additional feature for analemmatic sundials . Ok, I am biased but... There is some useful information on such things as shadow lengths and seasonal markers on my fairly primitive personal website http://www3.telus.net/public/rtbailey/ Regards, Roger Bailey Walking Shadow Designs N 48.6 W 123.4 Sidney by the Sea, BC -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]On Behalf Of Tracy PaineSent: October 26, 2006 5:55 PMTo: sundial@uni-koeln.deSubject: date scale Hello Thank you Chris. In regards to your question, the major axis of my sundial is 33 feet. I used large basalt rocks for the hour marks. I tried to send a picture of it here, but the file was too big I guess. I plan to mosaic the top of the concrete date scale after it is cured. I would like to depict the analemma itself, colored according to the seasons with the months marked around it. Tracy --- https://lists.uni-koeln.de/mailman/listinfo/sundial
date scale
Hello Thank you Chris. In regards to your question, the major axis of my sundial is 33 feet. I used large basalt rocks for the hour marks. I tried to send a picture of it here, but the file was too big I guess. I plan to mosaic the top of the concrete date scale after it is cured. I would like to depict the analemma itself, colored according to the seasons with the months marked around it. Tracy --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: date scale
Hi Tracy, The date scale should be on the N-S centreline of the elliptical dial (i.e. the minor axis of the ellipse). The position of the 12 noon point is irrelevant. 3 feet by 10 feet is a big scale. How big is the dial? Regards Chris - Original Message - From: Tracy Paine To: sundial@uni-koeln.de Sent: Thursday, October 26, 2006 8:51 PM Subject: date scale Hello everyone! Thank you all for the help you gave me previously regarding "finding true north." I am now going to be pouring concrete for the date scale in my ananemmatic sundial. I am making the concrete pad 3 feet wide and 10 feet long. I have one question: do I lay out the center line of the scale on the N-S axis, or do I lay it out on the 12:00 noon axis? The noon hour on the sundial is 10 inches off the N-S line. I appreciate your help. Thank you. Tracy ---https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
date scale
Hello everyone! Thank you all for the help you gave me previously regarding "finding true north." I am now going to be pouring concrete for the date scale in my ananemmatic sundial. I am making the concrete pad 3 feet wide and 10 feet long. I have one question: do I lay out the center line of the scale on the N-S axis, or do I lay it out on the 12:00 noon axis? The noon hour on the sundial is 10 inches off the N-S line. I appreciate your help. Thank you. Tracy --- https://lists.uni-koeln.de/mailman/listinfo/sundial
