Re: Sundial designs against vandalism

[Gian Casalegno]

I have been asked about a link to the Compendium article I quoted im my
previous email.

Well that article is not actually available but almost the same content is
included in the following presentation :
  http://www.sundials.eu/download/bifilareENU.pdf

Moreover an example of the results you can obtain with the program can be
seen in this simulation made with SketchUp :
  https://youtu.be/tD22oba6RyQ

Ciao.
Gian

Il giorno ven 27 set 2019 alle ore 22:40 Gian Casalegno <
gian.casale...@gmail.com> ha scritto:

> David,
> have a look at the bifilar sundials article on The Compendium 24-2 :
> "Bifilar sundials within everyone's means" (let me know if you cannot reach
> it).
> Then download the "Orologi Solari" program that can be used to design
> almost every kind of bifilar sundials.
> And let me know about every doubt you may have.
> Kind regards.
> Gian Casalegno
>
> Il giorno ven 27 set 2019 alle ore 17:33 David Andersson <
> davey.anders...@gmail.com> ha scritto:
>
>> In message <
>> caokdy5chx5cvb8u1wt6vfbkmydurwp7z4pkz_jg6o5li4pa...@mail.gmail.com>
>>   Michael Ossipoff  wrote:
>>
>> > I like the pond suggestion, It hadn't occurred to me, and I hadn't
>> heard it
>> > before.
>> >
>> > Michael Ossipoff
>> > 40 F
>> > September 27th
>> > 1101 UTC
>>
>>
>> Just like yourself, I never thought of using a surrounding water-
>> barrier to protect any sundial from vandalism - but I tend to
>> agree with the people who see that an interactive Analemmatic is
>> probably best, and is almost intuitive how it works (so no great
>> explanation, apart from "stand on today's date" is necessary).
>>
>>
>> However, I would like to have some further information on the
>> "bi-filar" sundial mentioned by Linda Reid - as I am intrigued
>> that the time is indicated by the INTERSECTION of shadows cast
>> by two horizontal gnomons.  I have never seen this type of dial,
>> so I would be grateful if anybody can send a diagram (or even a
>> photograph) of one to this Mailing List - plus if it is 'equi-
>> angular', I can see that it will be much easier to manufacture.
>>
>> I assume the two horizontal gnomons have to be 'adjustable' in
>> some way, if the dial has to deal with Latitude variations - and
>> with Longitude/EoT being dealt with, by rotating its Hour-ring?
>>
>>
>> Regards,
>>
>> David Andersson.
>>
>>
>> --
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
---
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RE: Sundial designs against vandalism

[Roger]

Rafael Soler Gaya has designed and built several robust and vandal resistant 
bifilar sundials. Most are in Mallorca and described in my presentation 
“Sundials in Mallorca” available here as a 28 MB 64 page Power Point file. 
https://drive.google.com/open?id=1jhijp42m2dacGNDIqg4WOx7Fyn3XKgrF

The cover picture showing the dial at Camp de Mar, Mallorca is here as a 150 kb 
JPG.
https://drive.google.com/open?id=1OsRUKFq0ujkd2qoa528D61dF1AG-nTWD

My favourite is the garden fountain bifilar. Here a water jet falling in in a 
parabolic curve and a chain hanging in a catenary curve form the intersecting 
bifilar shadows on the vertical wall.

His techniques are described in the NASS Compendium V13-4 Dec 2006 and the BSS 
Bulletin 22 (IV) 34-37)

Roger bailey
Walking Shadow Designs
N 48.6, W 123.4



From: César Busto
Sent: September 29, 2019 8:34 AM
To: sundial@uni-koeln.de
Subject: Sundial designs against vandalism (Cesar Busto)

A robust and anti-vandalism solution would be to build a bifilar sundial with 
two vertical walls whose heights correspond to a classic bifilar .

By adding an hole to the N-S wall, you could trace an analemma.

César Busto



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Re: Sundial designs against vandalism

[Peter Mayer]

Hi,

My favourite example of a robust public dial is the Dodwell dial located in 
Adelaide, South Australia. As (I hope) the appended photo shows, it is a 
variant of a polar dial, which, in effect, has been split in two, with the 
resulting gnomons moved to the outer edges. It has been in situ since about 
1942 with no evidence of vandalisation.

best wishes,

Peter

On 26/09/2019 3:59 am, Dan-George Uza wrote:
Hello,

Horizontal sundials are often victims of vandalism. I am looking for ideas or 
designs of gnomons which are not that easy to break off i.e. how to attach them 
permanently to the base plate.  Can you help?

Thanks,

--
Dan-George Uza



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--
Peter Mayer
Department of Politics & International Studies (POLIS)
School of Social Sciences
http://www.arts.adelaide.edu.au/polis/
The University of Adelaide, AUSTRALIA 5005
Ph : +61 8 8313 5609
Fax : +61 8 8313 3443
e-mail: peter.ma...@adelaide.edu.au
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Re: Sundial designs against vandalism

[Gian Casalegno]

David,
have a look at the bifilar sundials article on The Compendium 24-2 :
"Bifilar sundials within everyone's means" (let me know if you cannot reach
it).
Then download the "Orologi Solari" program that can be used to design
almost every kind of bifilar sundials.
And let me know about every doubt you may have.
Kind regards.
Gian Casalegno

Il giorno ven 27 set 2019 alle ore 17:33 David Andersson <
davey.anders...@gmail.com> ha scritto:

> In message <
> caokdy5chx5cvb8u1wt6vfbkmydurwp7z4pkz_jg6o5li4pa...@mail.gmail.com>
>   Michael Ossipoff  wrote:
>
> > I like the pond suggestion, It hadn't occurred to me, and I hadn't heard
> it
> > before.
> >
> > Michael Ossipoff
> > 40 F
> > September 27th
> > 1101 UTC
>
>
> Just like yourself, I never thought of using a surrounding water-
> barrier to protect any sundial from vandalism - but I tend to
> agree with the people who see that an interactive Analemmatic is
> probably best, and is almost intuitive how it works (so no great
> explanation, apart from "stand on today's date" is necessary).
>
>
> However, I would like to have some further information on the
> "bi-filar" sundial mentioned by Linda Reid - as I am intrigued
> that the time is indicated by the INTERSECTION of shadows cast
> by two horizontal gnomons.  I have never seen this type of dial,
> so I would be grateful if anybody can send a diagram (or even a
> photograph) of one to this Mailing List - plus if it is 'equi-
> angular', I can see that it will be much easier to manufacture.
>
> I assume the two horizontal gnomons have to be 'adjustable' in
> some way, if the dial has to deal with Latitude variations - and
> with Longitude/EoT being dealt with, by rotating its Hour-ring?
>
>
> Regards,
>
> David Andersson.
>
>
> --
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
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Re: Sundial designs against vandalism

[Steve Lelievre]

Assuming the question relates to the gnomon of a traditional Horizontal
Dial, then perhaps use a design with a very wide gnomon. That ought to make
it harder to bend it, and gives more contact area on the dial faces for
more screws.

Steve

On Thu, Sep 26, 2019 at 01:00, Dan-George Uza 
wrote:

> Hello,
>
> Horizontal sundials are often victims of vandalism. I am looking for ideas
> or designs of gnomons which are not that easy to break off i.e. how to
> attach them permanently to the base plate.  Can you help?
>
> Thanks,
>
> --
> Dan-George Uza
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
> --
Cell +1 778 837 5771
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Re: Sundial designs against vandalism

[David Andersson]

In message 
  Michael Ossipoff  wrote:

> I like the pond suggestion, It hadn't occurred to me, and I hadn't heard it
> before.
> 
> Michael Ossipoff
> 40 F
> September 27th
> 1101 UTC


Just like yourself, I never thought of using a surrounding water-
barrier to protect any sundial from vandalism - but I tend to
agree with the people who see that an interactive Analemmatic is
probably best, and is almost intuitive how it works (so no great
explanation, apart from "stand on today's date" is necessary).


However, I would like to have some further information on the
"bi-filar" sundial mentioned by Linda Reid - as I am intrigued
that the time is indicated by the INTERSECTION of shadows cast
by two horizontal gnomons.  I have never seen this type of dial,
so I would be grateful if anybody can send a diagram (or even a
photograph) of one to this Mailing List - plus if it is 'equi-
angular', I can see that it will be much easier to manufacture.

I assume the two horizontal gnomons have to be 'adjustable' in
some way, if the dial has to deal with Latitude variations - and
with Longitude/EoT being dealt with, by rotating its Hour-ring?


Regards,

David Andersson.


-- 
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Re: Sundial designs against vandalism

[Michael Ossipoff]

I like the pond suggestion, It hadn't occurred to me, and I hadn't heard it
before.

Michael Ossipoff
40 F
September 27th
1101 UTC
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Re: Sundial designs against vandalism

[Michael Ossipoff]

Of course a steel gnomon securely fastened would be harder to break off. Of
course you already know that people have suggested high-mounted vertical
wall-dials. Of course, for those, for security, you wouldn't want one of
those horizontal nodus-sticks. You'd want the usual downward-slanted gnomon.

We hear the good suggestion of the vandal-proofness of an analemmatic dial,
but I prefer a dial whose construction-principle can be easily explained to
anyone. You wouldn't want to try to explain the analemmatic's construction
to anyone other than at least a very-interested secondary-school or
pre-secondary-school student.

Any non-declining flat-dial's construction-principle is easily-explained.
That includes a horizontal dial, an equatorial-dial, a north or south
vertical dial, or a north or south reclining (but not declining) dial.

In fact, it should be mentioned that even a vertical-declining dial's
hour-line construction can be derived and explained without spherical trig
or spherical co-oridinate transformations.  (...though declination-lines
for it would still require them).

Michael Ossipoff
Week 40, Friday
September 27th
1050 UTC


On Thu, Sep 26, 2019 at 4:00 AM Dan-George Uza 
wrote:

> Hello,
>
> Horizontal sundials are often victims of vandalism. I am looking for ideas
> or designs of gnomons which are not that easy to break off i.e. how to
> attach them permanently to the base plate.  Can you help?
>
> Thanks,
>
> --
> Dan-George Uza
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
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Re: Sundial designs against vandalism

[Linda Reid]

In message 
  Dan-George Uza  wrote:

> Hello,
> 
> Horizontal sundials are often victims of vandalism. I am looking for ideas
> or designs of gnomons which are not that easy to break off i.e. how to
> attach them permanently to the base plate.  Can you help?
> 
> Thanks,
> 


Hi, Dan

If you are interested in 'large-scale' public sundials, which are
virtually vandal-proof - then just create an Analemmatic, using a
person's own shadow to tell the time.  It will be interactive, as
well as not needing a gnomon at all - and can be made from a wide
range of materials (stone/concrete/mosaic/wood/metal/etc) to suit
the location.  If set into grass, then just 'mow' right over it !

Alternatively, for a 'pedestal-mounted' type dial, then just make
it in the bi-filar form - by using (say) 1cm diameter steel tubes
to create the North/South and East/West horizontal gnomons, whose
shadow intersection shows the time.  Any normal vandal would find
it very difficult to bend such tubes.  This also has an advantage
of being 'equi-angular', (with 15 degrees between each hour) - so
could be simple to rotate its Hour-ring either for any 'Daylight-
saving' time changes, and/or to accommodate the Equation-of-Time.

Sincerely,

Linda Reid.

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Re: Sundial designs against vandalism

[fabio.sav...@nonvedolora.it]

dear Dan

I think one of the better way is to create a pool with few centimeters 
of water around the sundial, small enough to allow to watch the dial, 
large enough to avoid to reach it.
The bottom of the pool may have white o black little stones to get more 
evidence for the sundial, this depends on the materials used for the 
sundial. Moreover the stones get more difficult to walk in, even without 
shoes.

It isn't dangerous for anyone but it is effective.
It may be necessary to circulate the water with an anti-algae.

It seems that vandals have very precious shoes, usually they have 
attentions only for themselves.


ciao Fabio


but it is very useful for other street works.

Il 26/09/2019 09:59, Dan-George Uza ha scritto:

Hello,

Horizontal sundials are often victims of vandalism. I am looking for 
ideas or designs of gnomons which are not that easy to break off i.e. 
how to attach them permanently to the base plate. Can you help?


Thanks,

--
Dan-George Uza

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--
Fabio Savian
fabio.sav...@nonvedolora.it
www.nonvedolora.eu
Paderno Dugnano, Milano, Italy
45° 34' 9'' N, 9° 9' 54'' E, UTC +1 (DST +2)

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Sundial designs against vandalism

[Dan-George Uza]

Hello,

Horizontal sundials are often victims of vandalism. I am looking for ideas
or designs of gnomons which are not that easy to break off i.e. how to
attach them permanently to the base plate.  Can you help?

Thanks,

-- 
Dan-George Uza
---
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