I also agree, also as a mock HORIZONTAL dial. The intended latitude Phi
should be related to the angle A between the 12 and 9 (or 3) hr lines
as: sin(Phi) = tan (A). [For a vertical direct south dial, change sin
into cos.] As A is clearly more than 45°, tan(A)>1, which is beyond the
reach of the sin as well as the cos function.
Best regards,
Frans Maes
On 1-6-2011 5:38, Roger Bailey wrote:
I agree with John and Jack, this dial is suffering from gnomon
dysfunction. This affects a lot of older sundials. The intended
gnomon was polar, not normal (perpendicular)..
Jack analyzed the hour lines and found that they are inconsistent. I
did similar limited tests and agree.
This sundial seems to be a mass produced brass plate item, not an
engraved and gnomonically correct sundial. The patterns on the dial
are easily mass produced as brass plate pressings. If this were the
"Antique Road Show" I would not place a significant value on this
sundial. Some things do not improve with age.
Regards, Roger Bailey Walking Shadow Designs
From: John Carmichael Sent: Monday, May 30, 2011 7:55 AM To: 'Sundial
List' Cc: i...@mediadesign.me Subject: FW: sundial /Jacopo de'Benci
Hi Jan- I'm forwarding your letter and my comments to the Sundial
List. Perhaps the sundial experts in our group can help you more
than I can!
_______________________________________________________________________________
Hello Dialists:
I received this letter inquiring about an old European sundial. I'm
not an expert on these things, so I'm forwarding the letter to you
guys. I've never heard of the maker- Jacopo de' Benci whose name is
inscribed on the dial.
Looking at the enlarged photo of it at
http://www.mediadesign.me/pollaiuolo/images/sonnenuhr-jacopo-de-benci-4.jpg
you can see it has a perpendicular rod gnomon, implying that at
first glance it is a nodus-based design. But the location of the
rod seems to be incorrectly located at the convergence of the hour
lines. I'm thinking that this dial was not designed to have a
perpendicular gnomon. It should have an angled polar axis gnomon (an
angled rod or a triangular sheet). Perhaps the rod was added to the
original attachment hole after the original polar axis gnomon fell
off at an earlier date.
Does my analysis seem correct?
Please copy your replies to Jan K. Botor at i...@mediadesign.me
Thx
John C.
From: info-mediadesign [mailto:i...@mediadesign.me] Sent: Monday, May
30, 2011 2:45 AM To: jlcarmich...@comcast.net Subject: sundial
/Jacopo de'Benci
Dear Mr Carmichael.
Mrs. Monika Leonhardt, M.A. (Uhrenmuseum Beyer Zürich) kindly
provided me with your contact details.
I am currently trying to investigate into the origin of this sundial
and I kindly ask you for your opinion as an expert about this piece
of applied art and your suggestion if it could possibly be authentic.
My personal opinion is that it is a copy of something made in the
19th Century but I can not locate anything similar whether in books
nor in the whole internet.
I put the details that I know, a summary of suggestions I received
3rd hand and high-resolution pictures at the following link:
http://www.mediadesign.me/pollaiuolo/index.html
It is my intention to give it to an department for dendrochronical
and spectroscopic analysis, as I got various information that
differs widely regarding the possible age and origin. It is
starting with suggestions, placing it around the early 19th century
and goes as far as it was possibly an early work by Pollaiuolo at the
goldsmith "Ghiberti" where Jacopo de' Benci was apprentice for
Metalwork.
That is well a wide range for speculations so, the coming analysis
will place the object in a probable timeframe, I hope .
I want to thank you in advance for your effort and It would be really
nice to hear your opinion and if a scientific analysis would be
advisable.
If it is of interest, as the photographs are may not sufficient I
would be glad to provide you with the original instrument for further
research.
With kind regards,
Jan K. Botor
Hauptstr.40 25704 Meldorf T 0178-7732125
i...@mediadesign.me www.mediadesign.me
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