Re: Summer Solstice in Florence

[Bill Gottesman]

Hello Claus,

Yes, in J. L. Heilbron's "The Sun in the Church" he reports that Toscanelli
designed the original meridian and solstice mark in 1510, placing a bronze
plaque at the sun's noon solstice image.  Around 1754 Leonardo Ximenes
discovered that Toscanelli's 1510 meridian was off by almost a full
degree.  The I remain confused regarding the two circles (elipses), as the
smaller circle is clearly north of the center of the larger circle.

Heilbron offers clues to the answer, but not a complete explanation: One is
that the original gnomon hole was created around 1475, and was "reset" in
1511, the year after the the brass marker was placed.  I do not know if
that means the gnomon hole was moved, or by how much.  Furthermore, I do
not see a brass marker, so this is confusing.  I think both of the circles
are stone, based on the video and other photos.  From 1510 to 1754 the
ecliptic tilt shrank about .03 degrees, which would have moved the center
of the solstice mark northward about 4.5 centimeters (my calculation).  The
smaller circle/ellipse is displaced northward from the lager ellipse, but
to me it looks like a distance much greater than 4.5 cm.  So I am stumped
here.  -Bill

On Thu, Jun 7, 2018 at 5:18 PM, Claus Jensen  wrote:

> The divided line or band to the left in the picture is Leonardo Ximenes’
> so-called *new* meridian line described in his 1757 book *Del vecchio e
> nuovo gnomone fiorentino*
> . It
> deviates slightly from the *old *meridian line, dating from ca. 1475, due
> to Paolo Toscanelli. The two circles are what remains of Toscanelli’s
> meridian line.
>
> According to a sketch in Ximenes’ book, the smaller circle is called *The
> solstice marble*. The greater circle contains a date, hardly visible
> today, given in the old roman calendar, corresponding to 12 June 1510 in
> the Julian calendar. Thus summer solstice in 1510 took place on 12 June.
>
>
> Claus Jensen, DK
>
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Re: Summer Solstice in Florence

[Bill Gottesman]

On Thu, Jun 7, 2018 at 3:19 PM, Willy Leenders 
wrote:

> Hi Bill,
>
> My answers on your questions are:
>
> 1.
> The light spot moves from the west to the east and the camera observes
> this from a position north of that displacement.
>
I agree. -Bill

>
> 2.
> The image of a circle projected by the sun is only a circle in an
> exceptional case. In all other cases it is an ellipse.
>
Yes, but in this case the ellipse appears elongated east-west, but it
should be elongated north-south.  I am guessing the low camera angle has
created this illusion of east-west elongation. -Bill

>
> 3.
> The inner circle indicates the right place, the outer circumference
> corresponds to the circumference of the light spot on that moment
>
Not sure I understand this.  -Bill

>
> Willy Leenders
> Hasselt in Flanders (Belgium)
>
> Visit my website about the sundials in the province of Limburg (Flanders)
> with a section 'worth knowing about sundials' (mostly in Dutch):
> http://www.wijzerweb.be
>
>
>
>
> Op 7-jun-2018, om 19:51 heeft Bill Gottesman het volgende geschreven:
>
> Thought provoking video.  Here are a two simple questions worth
> contemplating:
>
> 1.  From what perspective is the video filmed?Is the camera roughly south,
> north, east,or west of the summer solstice mark?
>
> 2.  Why does the sun appear elongated in its right-to-left direction of
> travel across the screen?  Is this at all surprising?
>
> And a hard one, the answer to which I am unsure:
> 3.  What is the purpose of constructing the smaller circle (or ellipse)
> inside of the larger one?
>
> -Bill
>
> On Thu, Jun 7, 2018 at 7:38 AM, J. Tallman  com> wrote:
>
>> Hello All,
>>
>> This morning I saw an article online about the upcoming summer solstice
>> that may be of interest:
>>
>> https://www.thelocal.it/20180606/florence-duomo-gnomon-summer-solstice
>>
>> Get your sundial prototypes ready to test, it won't be long before the
>> special moment comes!
>>
>>
>> Best,
>>
>> Jim Tallman
>> www.spectrasundial.com
>> www.artisanindustrials.com
>>
>> jtall...@artisanindustrials.com
>> 513-253-5497
>>
>> This message is being sent remotely as I am currently out of the studio.
>> Please excuse any further delay in response.
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
> Willy Leenders
> Hasselt in Flanders (Belgium)
>
> Visit my website about the sundials in the province of Limburg (Flanders)
> with a section 'worth knowing about sundials' (mostly in Dutch):
> http://www.wijzerweb.be
>
>
>
>
>
>
>
>
---
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Re: Summer Solstice in Florence

[Willy Leenders]

Hi Bill,

My answers on your questions are:

1.
The light spot moves from the west to the east and the camera observes this 
from a position north of that displacement

2.
The image of a circle projected by the sun is only a circle in an exceptional 
case. In all other cases it is an ellipse.

3.
The inner circle indicates the right place, the outer circumference corresponds 
to the circumference of the light spot on that moment

Willy Leenders
Hasselt in Flanders (Belgium)

Visit my website about the sundials in the province of Limburg (Flanders) with 
a section 'worth knowing about sundials' (mostly in Dutch): 
http://www.wijzerweb.be




Op 7-jun-2018, om 19:51 heeft Bill Gottesman het volgende geschreven:

> Thought provoking video.  Here are a two simple questions worth contemplating:
> 
> 1.  From what perspective is the video filmed?Is the camera roughly south, 
> north, east,or west of the summer solstice mark?
> 
> 2.  Why does the sun appear elongated in its right-to-left direction of 
> travel across the screen?  Is this at all surprising?
> 
> And a hard one, the answer to which I am unsure:
> 3.  What is the purpose of constructing the smaller circle (or ellipse) 
> inside of the larger one?
> 
> -Bill
> 
> On Thu, Jun 7, 2018 at 7:38 AM, J. Tallman  
> wrote:
> Hello All,
> 
> This morning I saw an article online about the upcoming summer solstice that 
> may be of interest:
> 
> https://www.thelocal.it/20180606/florence-duomo-gnomon-summer-solstice
> 
> Get your sundial prototypes ready to test, it won't be long before the 
> special moment comes!
> 
> 
> Best,
> 
> Jim Tallman
> www.spectrasundial.com
> www.artisanindustrials.com
> 
> jtall...@artisanindustrials.com
> 513-253-5497
> 
> This message is being sent remotely as I am currently out of the studio. 
> Please excuse any further delay in response.
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
> 
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

Willy Leenders
Hasselt in Flanders (Belgium)

Visit my website about the sundials in the province of Limburg (Flanders) with 
a section 'worth knowing about sundials' (mostly in Dutch): 
http://www.wijzerweb.be







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Re: Summer Solstice in Florence

[Bill Gottesman]

Thought provoking video.  Here are a two simple questions worth
contemplating:

1.  From what perspective is the video filmed?Is the camera roughly south,
north, east,or west of the summer solstice mark?

2.  Why does the sun appear elongated in its right-to-left direction of
travel across the screen?  Is this at all surprising?

And a hard one, the answer to which I am unsure:
3.  What is the purpose of constructing the smaller circle (or ellipse)
inside of the larger one?

-Bill

On Thu, Jun 7, 2018 at 7:38 AM, J. Tallman 
wrote:

> Hello All,
>
> This morning I saw an article online about the upcoming summer solstice
> that may be of interest:
>
> https://www.thelocal.it/20180606/florence-duomo-gnomon-summer-solstice
>
> Get your sundial prototypes ready to test, it won't be long before the
> special moment comes!
>
>
> Best,
>
> Jim Tallman
> www.spectrasundial.com
> www.artisanindustrials.com
>
> jtall...@artisanindustrials.com
> 513-253-5497
>
> This message is being sent remotely as I am currently out of the studio.
> Please excuse any further delay in response.
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
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RE: Summer Solstice in Florence

[Dave Bell]

Thanks for the link, Jim!  A lovely spectacle.

On the slightly negative side, it never ceases to amaze (or amuse) me, the 
number of idiots that take flash photos of scenes of light. Same with the 
thousands of puny firefly flickers in the stadiums, serving only to light up 
the heads of the people directly in front of them…

 

Dave

 

From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of J. Tallman
Sent: Thursday, June 7, 2018 4:38 AM
To: Sundial Mailing List 
Subject: Summer Solstice in Florence

 

Hello All,

This morning I saw an article online about the upcoming summer solstice that 
may be of interest:

https://www.thelocal.it/20180606/florence-duomo-gnomon-summer-solstice

Get your sundial prototypes ready to test, it won't be long before the special 
moment comes!



Best,

Jim Tallman

www.spectrasundial.com  

www.artisanindustrials.com  

jtall...@artisanindustrials.com  

513-253-5497

This message is being sent remotely as I am currently out of the studio. Please 
excuse any further delay in response.

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