Hi Dan, You are asking the right questions. How large should the dial be, considering the users, adults or children? To answer this question I wrote a spreadsheet that calculated how long the shadow would be on any given date and height of the gnomon. Helmut Sonderegger improved the spreadsheet making it useful for European versions of Excel. Since then he incorporated the logic into a stand alone program available as "Alemma" on his website http://www.helson.at/sun.htm. Not only does this program show shadow lengths for times dates and heights, but it show where to place seasonal markers to indicate when and where the sun rises and set through the year. I my view Helmut's program is the go to program for designing analemmatic sundials. You can Ignore "Sunclock" marketers around the world.
Here is the quick response to your question. The size of 5.4m is a good compromise. I recommend up to 6 m for adults and around 5.2 for school children. I have used concrete paver with footprints for the date table and posts as hour harks for a simple analemmatic sundial at the Calgary Science Centre. See http://sundials.org/index.php/component/sundials/oneDial/668 and http://sundials.org/index.php/component/sundials/oneDial/668 for a couple of analemmatic sundials I designed in Calgary Alberta. The latter has seasonal markers. My final advice is don't include an analemma to correct for EoT unless it is a split analemma, providing different correction for am and pm. Helmut's Alemma handles split analemmas but in general, don't go there as the complexity outweighs the utility. Regards, Roger Bailey Walking Shadow Designs From: Dan Uza Sent: Wednesday, July 01, 2015 11:19 AM To: [email protected] Subject: Analemmatic sundial question Hello, >From your experience, what is the best analemmatic sundial size to be set up >at a children playground? I was thinking about a width of 5.4 meters, the base >consisting of a row of 4 concrete pavement tiles (40x40 cm) and 12 other >smaller tiles for the hours. Should their surface be more smooth or more >rugged? Also, can you please share some tips and tricks on how to mark the >months and hours? I was thinking about applying acrylic paint thorough some >PVC homemade stencils, but am not sure whether it will withstand traffic. Do I >need primer or lacquer? In any case, something cheap would be great :) Your insight is always appreciated. Dan Uza Romania -------------------------------------------------------------------------------- --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial -------------------------------------------------------------------------------- No virus found in this message. Checked by AVG - www.avg.com Version: 2015.0.6037 / Virus Database: 4365/10139 - Release Date: 07/01/15
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