Re: Interesting sundial in Japan

Roger Bailey Wed, 29 Apr 2009 09:27:47 -0700

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 34º. 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" <[email protected]>
Sent: Wednesday, April 29, 2009 7:01 AM
To: <[email protected]>; <[email protected]>
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" <[email protected]>

To: "Sundial List" <[email protected]>
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
<[email protected]> 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
[email protected]

---------------------------------------------------
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

L34V.pdf
Description: Adobe PDF document

---------------------------------------------------
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Interesting sundial in Japan

Reply via email to