To all sundialists,
I cannot refrain from inverting Willy's statement. I would say 'Tell the
people that sundialsgain or lose compared to the time which governs the
universal laws of physics'.
/Solar/ time (indicated by whatever type of sundial) maps time
differently and unevenly depending onthe chosen design and on
timevariant properties of our planet.These properties are 'natural' but
not essential.
I love sundials very much but I suggest not to tell anyone that our
quartz watches or atomic clocks gain and lose to the solar (so called
natural) time. The reference quantity is the physical time. However,
solar time is a nice, romantic, and historic approximation of time and
its indicators are fascinating.
Of course the subject is a matter of taste and discussing it can
degenerate to a round-ender-sharp-ender-contradistinction. My mission is
just to add to Willy's concern that sundials should not be enobled too
much by us. The watch should remain the reference instrument to the
sundial. Anyhow, a sundial with a big error can be an exeeding valuable
instrument.
Helmut Haase
Lemgo (Germany)
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Am 17.08.2016 21:15, schrieb Willy Leenders:
To all sundialists,
All that stuff is the result of the irresistible urge to let indicate
the time of a watch by a sundial.
A sundial is intended to indicate the solar time.
It is the only simple instrument that can do it.
In order to indicate the artificial time, which we have created to
practical reasons, we have a watch and many other devices.
Tell the people that our watch gains or loses compared to the real
natural time and that a sundial indicates this natural time, a watch
the artificial time.
And use your knowledge of mathematics for more useful purposes!
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 17-aug-2016, om 19:51 heeft fabio.savian het volgende geschreven:
thank you Willy and Fred for your notes,
I know an analemmatic sundial may have sophisticated versions to show
mean time, Fred your article is exhaustive, but I think it isn't the
better kind of sundial to give this info and to get a precison time
(position on the heels or on the middle of the feet, how vertical is
the hand rising above the head, estimation of the direction of the
shadow, graduations of the minutes, etc). Conversely it is a very
powerful instrument to involve people with gnomonics.
Anyway I think a simple analemma on the meridian line, without
explain its huge limits, is not an option, it is an error.
thank you, ciao, Fabio
Fabio Savian
Inviato da Tablet Samsung.
-------- Messaggio originale --------
Da: Fred Sawyer <fwsaw...@gmail.com <mailto:fwsaw...@gmail.com>>
Data: 16/08/2016 20:37 (GMT+02:00)
A: "fabio.savian" <fabio.sav...@nonvedolora.it
<mailto:fabio.sav...@nonvedolora.it>>
Cc: Sundial Group <sundial@uni-koeln.de <mailto:sundial@uni-koeln.de>>
Oggetto: Re: Double analemma dials
Hi Fabio
This use of an analemma design on the analemmatic dial has been a
confusing error that goes back at least to the early 20th century
introduction of the curve on the dial in Brou, France. The use of a
double analemma design with curves calculated to limit error to just
a few minutes throughout the year goes back at least to 1970 and the
work of Ken Seidelman at Longwood Gardens in Pennsylvania. For a
detailed discussion with equations, etc. see my article "Of
Analemmas, Mean Time and the Analemmatic Sundial" that you can
download at https://dl.dropboxusercontent.com/u/4837615/scia7.pdf
Brian Albinson has taken this idea to heart and, using a slightly
different approach to the equations, has designed several such dials
in the Vancouver area.
Fred Sawyer
On Tue, Aug 16, 2016 at 12:23 PM, fabio.savian
<fabio.sav...@nonvedolora.it <mailto:fabio.sav...@nonvedolora.it>> wrote:
hi all,
I draw inspiration from the image sent by Brian Albison for a
meditation.
I often found analemmatic sundials with the analemma. Has it a
sense ?
Standing on the analemma one can get the right correction for eot
only at noon.
Most of these sundials don't report a warning about it, so the
users get a wrong time al the day, except noon.
Moreover some of them haven't the calendar on the meridian line
but only on the analemma, so the misunderstanding is sure.
The use of a table with the eot should solve the curiosity to get
the mean time, so I wonder why this kind of sundial
is knowspreading with the analemma while it is not suitable for this.
Do you where this use come from ?
ciao Fabio
Fabio Savian
Inviato da Tablet Samsung.
-------- Messaggio originale --------
Da: Brian Albinson <brianalbin...@shaw.ca
<mailto:brianalbin...@shaw.ca>>
Data: 16/08/2016 18:04 (GMT+02:00)
A: Sundial Group <sundial@uni-koeln.de
<mailto:sundial@uni-koeln.de>>
Oggetto: Double analemma dials
Hi folk
We have built 3 direct reading mean time double analemma dials,
(including the Highlands School dial) in the Vancouver area and are
curious to know if any others exist in the world (apart from the
Longwood dial).
Brian Albinson
Len Berggren
Vancouver, Canada
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