Dear Roger, Thank you for creating this diagram. I'm sure this confirms that the hour lines on the bottom half of the ring are correct. The upper half of the ring seems to have equally-spaced lines. To my mind this spoils the symmetry, but it does not interfere with the functionality of the sundial as the upper half is not used.
I agree with Fred that it's a pity the dial surfaces seem to be too reflective to show shadows clearly. Perhaps the dots are not - those between 12:00 and 12:30 seem dark. But so do many of the others, pretty much at random as far as I can see. I am a little surprised that the hour lines are not continued on the inner cylindrical surface, as the shadows there would surely be stronger than on the south-facing ring. Regards Chris ----- Original Message ----- From: "Roger Bailey" <rtbai...@telus.net> To: "John Foad" <john.f...@keme.co.uk>; <sundial@uni-koeln.de>; <fwsaw...@aya.yale.edu> Sent: Wednesday, April 29, 2009 5:26 PM Subject: Re: Interesting sundial in Japan In questions like this, I use the engineering philosophy. "Don't speculate. Calculate". Attached is a quick drawing of the proper hour lines for a vertical dial for latitude 34ยบ. To me this looks like the hour lines on the vertical ring. Assuming the gnomon is polar and intersects the plane of the dial at the 6 o'clock line, this looks to me to be a gnomonically correct sundial. The top half of the ring is artistic rather than useful but the bottom half looks like a correct vertical sundial with the hour displayed on a ring. Rotate an equatorial ring on the 6 o'clock line to make it vertical and the hour angles on the ring change as shown in the drawing and on the sculpture. In this case I agree with John's analysis. Roger Bailey Walking Shadow Designs -------------------------------------------------- From: "John Foad" <john.f...@keme.co.uk> Sent: Wednesday, April 29, 2009 7:01 AM To: <sundial@uni-koeln.de>; <fwsaw...@aya.yale.edu> Subject: Re: Interesting sundial in Japan > > Hi Fred, > > If you print a copy of the picture, you can see that the style does at > least > pass through the line 6 - 18 and 12 - 24, so that is OK. I can't check > the > angles from the photo, but Tokushima is about 34 North, and the gnomon > angle > could be that (to the horizontal). As a fairly low-latitude dial (by UK > standards anyway!) the range of hour angles will not be as wide as I am > used > to, but they do look to be narrower at noon and wider at dusk, as they > should. I agree the designer may have had more interest in creating a fun > sculpture than primarily a dial, but he could nevertheless have got the > gnomonics right. > > Regards, > > John > ----- Original Message ----- > From: "Fred Sawyer" <fwsaw...@gmail.com> > To: "Sundial List" <sundial@uni-koeln.de> > Sent: Wednesday, April 29, 2009 2:28 PM > Subject: Interesting sundial in Japan > > > Perhaps I'm missing something, but it seems to me that this dial is > getting more attention than it deserves. It looks to me to be one of > those very expensive 'sculptures' made by an artist who really does > not understand how a dial works. This dial is not made right - it > will not indicate the correct time - the relationship between the > plane of hour lines and the gnomon is all wrong. The markings don't > appear to me to be braille-like. They are simply 3 pips on the hour > and 2 pips every 10 minutes. The fact that some of the pips aren't > visible is probably just a trick of lighting in this particular photo. > > As I said - unless I've missed something here - this is a 'dial' I > would pass by without paying it any heed. > > Fred > > > On Tue, Apr 28, 2009 at 12:29 PM, J. Tallman > <jtall...@artisanindustrials.com> wrote: >> Hello All, >> >> Here is a dial in Japan that I thought some of you may find interesting: >> >> http://commons.wikimedia.org/wiki/File:Sundial_bunkanomori_tokushima.jpg >> >> I have seen it a couple times in the past month while casually browsing >> for >> sundial pictures, but I have never been able to find a good description >> for >> it. Does anyone know about this dial? I would be interested in what some >> of >> you think is really going on here, since this is a pretty unique >> configuration. >> >> >> Best, >> >> Jim Tallman >> www.artisanindustrials.com >> jtall...@artisanindustrials.com >> >> --------------------------------------------------- >> https://lists.uni-koeln.de/mailman/listinfo/sundial >> >> >> > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.287 / Virus Database: 270.12.6/2084 - Release Date: 04/28/09 > 06:15:00 > ---------------------------------------------------------------------------- ---- > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
