Re: No more leap seconds!

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

Dear all, I have never commented on this topic, I do it now with a proposal.

- The leap second takes into account a sort of 'noise', unpredictable 
before, for small variations in the speed of the Earth's rotation.
Anyway, over the millennia this speed will decrease, so the leap second 
is not enough but the 'physical' second will deviate from the 
'astronomical' one.
The physical one is necessary to measure the astronomical one and they 
are two different things despite the attempts of recent centuries to 
make them equivalent


- Martian days have a different second, residents will use the physical 
second as unit of measurement for their scientific instrument but they 
will want to live a 24-hour day (in any case full hours) with an 
astronomical second significantly different from the physical one.


- At the end of the 18th century the meter was calibrated as 1/1 of 
the distance between the equator and the pole, it was later found that 
the measurement is a few kilometers more and also changes from one 
meridian to another, not to mention the equator.
This did not change the unit of measurement and did not impose a wrong 
measurement of the Earth. It is accepted that the meter has an 
autonomous definition distinct from the geographic measurements of the 
planet.


In my opinion the problem is in the name: the 'second' is a name that 
derives from a fraction of the day while the physical second is a unit 
of measurement that is still unnamed.
If the physical second had a definition, it would help put an end once 
and for all between the demands of scientific measurement and the rhythm 
of a planet's days.
The gnomonists are the most focused community on the history of time for 
which I am launching a proposal:
help the scientific world to find a definition for the physical second, 
giving it a separate identity from the local astronomical second (Earth, 
Mars, etc.).
This forum could be the place to put forward some shared proposal and 
start using it.
It does not matter if the scientific community wants to change it, it 
would still be a success to have established that the physical second 
has a different name and identity from our dear old terrestrial second. 
That of clocks and sundials, and of our terrestrial life.


Long live the second, ciao Fabio


Il 21/11/2022 17:39, Steve Lelievre ha scritto:



Ah, the joys of Listservs and email software. My participation 
sometimes gets of of step too: occasionally, original posts reach me 
after other people's replies.


Perhaps it wouldn't be a problem if all the world's computers were 
exactly synchronized... perhaps they could use atomic clocks for that 
  ;-)


Cheers,

Steve


On 2022-11-21 12:04 a.m., John Pickard wrote:


Sorry Steve,

I sent my post before seeing yours.

--
Cheers, John.

Dr John Pickard.



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


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

Re: Republican Calendar, Year 231

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

Dear Michael

The idea of reviving the Rep. Calendar (together with the corresponding 
Greg. Calendar) is that of an intellectual fun and I would be amazed to 
discover other implications.


There are many calendars still in use in the world even if to give us an 
appointment it has become common to refer to the Gregorian  Calendar.
If you really wanted a calendar to be hooked with precision to the 
declination curves, I believe that the most authoritative is the Persian 
Calendar, still in use in Iran and Afghanistan, which uses the names of 
the zodiac for its months, that is, equating what gnomonists usually do.


I don't think that the creators of the Rep. Calendar had the intention 
of reinterpreting the names of the zodiacal months (30° of longitude) 
with those of their calendar even if, despite a bit of approximation, 
these name could be a curious and entertaining option for people fasting 
in astronomy but able to perceive the meaning of these names.

With all the limitations of this option by varying the latitude.

If I really had to make some considerations on declination curves, I 
must say that lately I have rediscovered the use of these curves to 
define diurnal arcs of whole hours, i.e. selecting the declination 
values corresponding to diurnal arcs of whole hours and indicating this 
duration on the curves.
There are not many sundials with these features but they exist and 
provide useful and not commonly available information (Sundial Atlas 
DE2758, CZ218, AT1291, IT14055, FR4881).

On the Rep. Cal. 230, today is the day of  'celebration of convictions' :-)

ciao Fabio

--
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)

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

Re: A mis-aligned vertical dial

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

dear John

there is a precise theoretical procedure to relocate a sundial so that 
it works correctly in a new location (for the hour lines).


In the most general case, the sundial must be placed with a new 
orientation so that the style keeps the polar orientation in the new 
location (thinking of the stylus and dial as one whole).
This condition provides for many orientations, all the orientations 
obtained by rotating the dial around the polar stylus.
The difference caused by these rotations is the meridian to wich the 
time marked will refere, that is, as well as orienting the polar style 
correctly, a rotation around the axis may be necessary for the marked 
time system to be correct (local sun time, time-zone sun time).


It seems a little bit complicated, indeed it is, but it can be solved.

If the new location is very close there are not all these complications, 
you have only to keep the same orientation.
If the difference are few degrees in declination of the wall, you can 
place the sundial not parallel to the wall (keeping polar the stylus), 
otherwise, as you write, you have to accept an error.
The error is not constant at the same time, it also changes with the 
declination of the sun, that is, it is seasonal.
The answer to your question is a three-dimensional graph, with time and 
declination of the sun on x and y axes and the error on the z axis.
The error doesn't depend on latitude but on the angle between the polar 
axis and the non-polar stylus.


Not last, there is a consideration similar to that of Lewis Carroll 
about the stopped clocks that strike the right time twice a day:
a non-polar stylus, whatever its orientation, always shows the correct 
time once a day, when the sun is in the hourly plane that contains the 
non-polar stylus and the polar axis. This plane relates to two times 12 
hours apart.
In the other times the error occurs according to the declination of the 
sun, cancelling itself every 12 hours, whit the max error about halfway.
The paradox would therefore be that accepting a little approximation in 
the direction of the stylus is not important. This is the reason why 
even in front of a wrong sundial there are those who can say that they 
saw it strike the right time.

If it were not a paradox it would be the end of gnomonics :-(

I think that few degrees of error in the direction of the stylus (2-3°) 
might be acceptable, but it also depends on the size of the sundial and 
therefore on the comparison between the accuracy in the reading and the 
error due to the non-polar stylus.


ciao Fabio

Il 08/11/2021 14:38, John Foad ha scritto:


If a vertical dial is relocated and now faces a few degrees east or 
west of its designed declination, you might expect it to run a few 
minutes slow or fast.  Has anyone ever tabulated the greatest error, 
and at what times and dates it occurs?  And does it make sense to 
think about the average error?  Clearly the errors depend on the 
latitude and the design declination, but for starters they could be 
tabulated just for a direct south dial at 52.5 degrees N,  and for a 
location move of 1, 2 and 5 degrees either way.  As the gnomon is no 
longer polar-pointing I imagine the maths is a bit hairy.


Best wishes,

John Foad


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


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

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

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


--
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)

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

Re: Strange analemmatic sundial - how does it work?

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

dear Steve,

I did a search.

At first I realize that the dial has equiangle hours, so it seems to me, 
if it is analemmatic sundial it means that the dial has the inclination 
to get this condition (e.g. UK744 www.sundialatlas.net/atlas.php?sun=UK744).
This condition allows to turn the dial to adapt it to the time of 
another longitude or to correct it for eot.


Than I thought that this condition is the same for an equinoctial dial 
and may be it is not an analemmatic sundial, but an equinctial dial 
adjustable for eot, so 'analemmatic' has this meaning.
The french page of wikepedia says the same of the english one: Cadran 
analemmatiqueE. Ducretet 
<https://fr.wikipedia.org/wiki/Eug%C3%A8ne_Ducretet>& L. Lejeune 
(Paris), fin du XIX^e siècle. L'analemme montre « l'équation de la 
fonction du temps » et permet la correction de ce que l'horloge lit.


I think something is lost, without the gnomon it is difficult to 
understand it.


I found a book on internet, Catalogue des instruments de précision, 
Lejuene, Ducretet (the two authors of the sundial and of others 
scientific instruments),  I found the book on sale on internet but also 
the possibility to consult it online 
(https://archive.org/details/cataloguedesins00parigoog). There is a 
section starting at page 222, Cosmographie, where there are:


n. 1898 Chronomètre solaire de Fléchet fig 500
n. 1809 Méridien universel sur pied fig 501

Unfortunately this figures are not present (not scanned)
So I search for 'Chronomètre solaire de Fléchet' and I found some pages like
http://www.mhs.ox.ac.uk/collections/imu-search-page/record-details/?thumbnails=on=2258=34749

http://www.tessier-sarrou.com/html/fiche.jsp?id=5754802=3=fr=20=2=1=

https://www.mhs.ox.ac.uk/collections/imu-search-page/record-details/?TitInventoryNo=42286=field==2257

and others. They are heliocronometers, that is equinoctial dial, with 
turnable dial and with a tilting lens to get the Sun beam on the analemma.


I think this misunderstanding of the definition on Wiki depends on the 
double meaning of 'analemmatic':

- with the analemma of eot
or
- azimuthal sundial with the gnomon adjustable for the declination of 
the Sun.


ciao Fabio



Il 31/05/2019 07:30, Steve Lelievre ha scritto:

Hello everyone,

The English language Wikipedia page on analemmatic sundials has a 
photo of a strange example at the National Polytechnic Museum, Sofia. 
See https://en.wikipedia.org/wiki/Analemmatic_sundial and scroll down 
to the last photo.


It's completely unlike any other analemmatic dial that I know of, so 
I'm struggling to understand it. Which part is the gnomon? Which part 
moves?  Why do the hours run counterclockwise (Sofia is northern 
hemisphere so presumably it was made for use there)?  Why is there a 
brace apparently welded to the dial face in front of the XII position? 
What angle is the dial face at?


So many questions!

In short, how does it work ... can anyone enlighten me?

Thanks,

Steve




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


--
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)

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

Re: Changing to Summer Time

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

Frank, I found also this:

ciao Fabio

Il 01/04/2019 10:08, Frank King ha scritto:

Dear All,

I was sent the attached instruction sheet for changing time on various 
kinds of equipment.  For a sundial, the advice is "Move one house to 
the right".


The sundial could have been better drawn; some kind of equatorial 
might have been a better choice.  Moving one house to the right would 
work if you live so close to the north pole that this takes you into 
the next time zone 15 degrees to the east.


The advice for an oven clock suggests you need a masters degree in 
electrical engineering.  I have a Ph.D. in electrical engineering but 
failed completely when attempting to change the clock on an oven.  I 
managed to set the timer to cook for an hour but changing the main 
clock defeated me.


Frank King
Cambridge, U.K.


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


--
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)

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

Gianni

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

Dear all,

I finished the words to express my feelings.
After Reinhold, yesterday also Gianni Ferrari left us.
Sorry, in this moment I can't add other words.

Fabio

--
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)

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

Re:

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

Dear Martha, please if possible transmit my condolences to the family of 
Reinhold,


He was a dear friend and I'm very sad.

Fabio

Il 26/03/2019 06:43, Martha A. Villegas V. via sundial ha scritto:

Diese Nachricht wurde eingewickelt um DMARC-kompatibel zu sein. Die
eigentliche Nachricht steht dadurch in einem Anhang.

This message was wrapped to be DMARC compliant. The actual message
text is therefore in an attachment.

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


--
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)

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

Re: Equinox, Full Moon and Easter

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

Dear Frank

the replay at your question is not easy.

I see some ways to find it:
- one is exhaustive, few lines of software could check how many times 
the naive rule is verified in the whole cycle. It isn't very smart but 
it may be useful to verify the other points
- to disassemble the algorithm finding where and when it intervenes to 
shift the date
- reformulate an approach to find when the sunday overlap the canonical 
full moon but I think I would find myself in the previous point, with 
the formulation of epacts of Clavius
- to consult the book of Tempesti where there are many kind of tables 
and considerations on this matter, may be the answer is already written.


At first I think to follow the last point, unluckily I lent the book and 
it come back to me in the next days, I'll come back on the matter as 
soon as the book returns to my hands.


Yesterday I went to sleep thinking about the 3rd point, obviously I 
didn't solve my question but I dreamed my 'Sunday': I was going to an 
heliodrome with an ice cream :-)


ciao Fabio

Il 22/03/2019 17:02, Frank King ha scritto:

Dear Fabio,

I think the Spencer-Jones algorithm is
now widely accepted as defining when
Easter will be observed (by both the
Roman Catholic Church and the Anglican
Church for the foreseeable future).

What is interesting is just how often
it produces the same date as the naive
rule of 'the first Sunday after the
first full moon after the equinox'.

This year is clearly an exception
because the algorithm and the
naive rule give different answers.

Do you know how often the algorithm
and the naive rule differ?

You are allowed to choose your own
defintion of 'Sunday'!

Ciao Frank




--
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)

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

Re: Equinox, Full Moon and Easter

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

Dear Frank,

... ANSI Standard Easter, I missed it, I hope none of the international 
authorities for the standards read this mailing-list :-)


Even Gauss took care of it but his algorithm doesn't manage some exceptions.

For those interested in the matter:
Algorithm to calculate the date of Easter, by Spencer Jones, from his 
book General Astronomy, pages 73-74, edition of 1922.
Published again in the Journal of the British Astronomical Association, 
vol. 88, page 91, december 1977.
Here it is reported that the algorithm was defined on 1876 and it 
appeared in the Butcher's Ecclesiastical Calendar.
Unlike the algorithm of Gauss, this hasn't exceptions and it runs for 
the Gregorian Calendar, starting from 1583.



The limits of the dates are march 22 and april 25.
The dates of Easter have a cycle of 5,700,000 years.
The most frequently date is april 19.

Example for 2019:
A=5, B=20, C=19, D=5, E=0, F=1, G=6, H=29, J=4, K=3, L=1, M=0, N=4, P=20
N=4 that is april, P+1=21

The Orthodox Easter follows the Julian Calendar, the algorithm is:


The cycle of the dates of the Julian Easter is 532 years.

Example for 2019:
A=3, B=3, C=5, D=20, E=4, F=4, G=14
N=4 april, G+1=15, in the Gregorian Calendar 15+13=28

ciao Fabio


Il 21/03/2019 15:35, Frank King ha scritto:

Dear Roger,

I note that you say:


My reference on this topic is The Sun in
the Church by J L Heilbron.

He is pretty sound on this and, as early
as page 3, notes that the time of the
equinox and the time of full moon depend
where you are on the planet.  He adds,
"as, of course does Sunday".

If everyone used the Julian Date then
they might all agree on the instant of
the equinox and the instant of full
moon but it seems most unlikely that
they would have similar agreement as
to what is meant by "Sunday".

It takes 48 hours from the start of a
given Sunday, just to the west of the
International Date Line, to the end of
the same Sunday, just to the east of
the Line.

Fabio has pointed out that Rome and
Jerusalem have been suggested as
candidate places for defining a
Canonical Sunday.  I too have read
this but I don't know where the
supposed primary source is.

I think Fabio's explanation is the
most plausible.  In essence, you
define an algorithm (albeit one
that is a bit suspect) and impose
a kind of ANSI Standard Easter :-)

As a former colleague once told me:
"The great thing about having Standards
is that there are so many of them."

You are one of the most-westerly
subscribers to this list so I think
a Bailey-Standard Easter would be
worth lobbying for.

You might thereby become a noted
Holy Man.  Be careful!

Very best wishes

Frank

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



--
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)

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

Re: Equinox, Full Moon and Easter

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

dear Roger,

The computation of Easter is a little bit complex, it follows some 
canonical rules.


There is an astronomical equinox but the canonical equinox is always the 
march 21.
I have notice from the ephemeris that this year the astronomic full moon 
is on the march 21 (1:43 UT), that is in the same date of the canonical 
equinox. Someone says that it should be calculate in Rome, others in 
Jerusalem, anyway it is wrong because the reference is the canonical 
full moon and it is calculated with the epact, that is the moon's age at 
January 1.
Clavius worked on calendar reform and he wrote the epact for 4000 years. 
This year the epact is 24.
This means I have to come back 24 days to find a canonical new moon, 
that is december 8.
Now I have calculate the spring new moon adding 30, 29, 30, 29 days. 
This rule needed to approximate the lunar cycle of about 29 and half.
Adding 30 + 29 + 30 days I get march 7, than I have to add 13 days to 
get the canonical full moon and I get march 20, that is one day before 
the canonical equinox.
For this reason the rule adds other 29 days reaching april 18, so Easter 
is on april 21.
To get the full moon from the new moon the rule adds 13 days and not 
14.76 because it starts from the observation of the first lunar sickle, 
that is about 30 hours later the astronomical new moon.


These are the canonical rules and they differ from the astronomical 
abservations because the aim was to avoid complex and contestable 
observations, keeping the approximation as small as possible.
Sometimes the rules create curious arrangement like this year: the 
canonical full moon of march is one day before the canonical equinox 
while the astronomical full moon is one day after the astronomical equinox.


There also are ecceptions, for example if the canonical full moon is on 
april 21 and it is saturday, Easter is not on sunday 22 but on sunday 
29. Someone says because in the first case the Catholic Easter overlap 
Passoverr but the reason is to avoid to celebrate the resurrection in 
the same days of the death of Christ (Coyne, G. V., Michael A. Hoskin, 
and O. Pedersen. Gregorian Reform of the Calendar Proceedings of the 
Vatican Conference to Commemorate its 400th Anniversary, 1582-1982, 1983).


These infos come from the book of Piero Tempesti, Il calendario e 
l'orologio (the calendar and the timepiece), 2006. Tempesti deeply 
analyze this matter and I have summarized what Bepi De Donà recently 
exposed on the italian mailing-list of gnomonics about this topic.


ciao Fabio


Il 20/03/2019 05:00, Roger ha scritto:


I always thought Easter Sunday was on the first Sunday after the first 
full moon after the spring equinox. This year at my location, time 
zone PDST, the equinox is at 2:59 pm Wed 20 March 2019. The full moon 
is about 4 hours later at 6:43 pm. Why is this Sunday not Easter and 
Friday not Good Friday. What about the Passover. It is also a month 
later. I know setting the date of Easter was the problem that inspired 
astronomy but this year the scientific data and the religious credo do 
not seem to agree.


Where have I been mislead? (other than finding silly girls posing as 
sundials)


Roger Bailey

Walking Shadow Designs

N 48.669°, W 123.403°


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


--
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)

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

Heliodrome

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

Dear Frank

every sundial has an heliodrome but its limits change with the 
orientation of the dial, its shape and other if it isn't plane.
I took a glance to the last sundials uploaded on Sundial Atlas in these 
days and I found a photo that is right for us.


(IT16648, photo by Roberto Incerti)
The light brown area is the heliodrome of the sundial because it is 
where one can read the Sun projection. The shadow of the gnomon (its 
edge) cannot leave the heliodrome.
The heliodrome of the wall is more extended because its limits are wider 
than those of the dial.
In the sky the heliodrom is among the apparent orbits of the Sun at 
solstices and the horizon.


ciao Fabio


Il 17/03/2019 12:47, Frank King ha scritto:

Dear Fabio,

Many thanks for your most interesting
message to the list...


Years ago Nicola Severino found
'eliodromo' in a book of Athanasius
Kircher...

Can you provide a photograph of an
eliodromo?  OR, perhaps, a photograph
of a suitable sundial with the region
of the eliodromo highlighted?

Frank

Frank King
Cambridge, U.K.



--
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)

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

Re: dischrony

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

ne is
offset from the other but this offset is in no
sense a correction!

To me "offset" is neutral.

There are, of course, many many different
times in current use.  Here are just a few:

  TAI, UTC, UT1, UT2, GMT, GST, GPS time

None of these is wrong but each is offset
from all the others.

Sometimes the offset is constant such as
the difference between TAI and GPS time

Sometimes the offset changes infrequently,
such as the difference between TAI and UTC
(which changes only when there is a leap
second).

Sometimes the offset changes continuously,
such as the difference between GST (sidereal
time) and GMT.

This suggests that the word 'constant' is
not generally appropriate and is why I am
not keen on the Italian "costante locale".

This is actually a false assertion when
referring to local mean time versus local
time-zone time because in most places the
reference time zone is shifted 15 degrees
backwards and forwards at the whim of
legislators!  The offset is not constant!

Dan-George asks:

  how would you translate the Italian
  "foro gnomonico"

In English, this translates literally as
"gnomonic hole" but this would be a bad
translation!  It generally refers to the
hole in the roof (or possibly a side wall)
of a cathedral or large church that lets
in the sun so as to cast an image of the
sun on the floor.

The best English equivalent is "aperture
nodus" but that isn't quite the same thing.
An aperture nodus provides a spot of light
on the dial plate, not an image of the sun.

The French "oeilleton" is more challenging!
In English, this translates literally as
"eye-cap" which I think of as something
for medical use, for washing your eyes.

I rather suspect that the French also use
this to mean aperture nodus but I should
like confirmation.

Frank

Frank King
Cambridge, U.K.

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

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

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


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


--
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)

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

dischrony

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

hi all, I've a matter to put to you.

In Italy some sundials show the written 'costante locale', that can be 
translated as 'local constant'.
The authors of these sundials use this expression meaning the time 
difference between the Local Sun Time and the Time-Zone Sun Time.
This 'local costant' is an angle if it highlights the difference of 
longitude or a time if it highlights the difference between the two Sun 
Time.


I don't really like this expression. I think that the term 'costant' is 
misleading: the shown value depends on the selected meridian, it could 
not be that of the Time-Zone (e.g, outside UK, the one of the national 
observatory used in the past).
Moreover the term suggests that there is a not better identified costant 
in that location but it isn't a costant, it is a choice on how to show 
the time.


I started to look for a more proper expression.
I'd like to know if there are any terms used in other languages, may be 
that a proper expression already exists.
Anyway I found two italian terms that I think to propose as an 
alternative to the italian diallists, these terms may be used also in 
english so I'd like to know your thoughts.
The first term is 'dislocation' (dislocazione), it means a different 
location and it refers to an angle.
The second one is 'dischrony' (discronia) and it means a different time. 
This terms is curious because it rarely appears on the italian 
dictionaries, it is a technical term used in the medical field to 
indicate the cause of the 'jet lag' (while dysrhythmia is used for the 
effects), that is: to live with a different time.


ciao Fabio


--
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)

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

Re: Accuracy of wristwatch as compass

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

dear Dan

the wristwatch as compass has 3 problems:
a) it shows the time of a different longitude, the one of the time-zone 
(GMT or DST).
You should correct it for the local time but it is possible only if you 
know your longitude.


b) you should correct the time also for eot, it means you should start 
with the local Sun time for the longitude where you'll use it.


You can admit a little bit of imprecision avoiding a) and b), if your 
longitude is not so far from the one of the time-zone.


c) you have to rotate the watch around the 3-9 axes of the colatitude 
angle, so you have to evaulate also your latitude.


Overall it isn't a reliable way to find the north, it is useful to have 
a rough estimate if you haven't other instruments.


I have some 3D drawings for a book I'm writing, I attach 2 images, if 
you wish I can send you, or anyone who request them, a more defined jpg.


ciao Fabio

--

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)

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

Sundial Atlas

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

Hi all, I've some news.

Sundial Atlas was born 8 years ago, on april 25th 2010, and today it has 
changed appearence.
In the last months I have worked on a new software, renewing the 
graphics, with a new faster server, with new features and, overall, with 
a new management system as planned when started.
Sundial Atlas is not my website but an international and public tool to 
spread gnomonics through the knowledge of the sundials so the new 
structure has a national referent for every country with an heritage of 
sundial.
These referents are the real management board of Sundial Atlas and they 
all together can run the project that must survive me (I'm well but I'm 
worried about the next century :-)    )


The new website has a guide for the users (home page, click 'Sundial 
Atlas' on the left, then click 'logo & guides').


If you need any info or if you have suggestions, or you find any bugs, 
plese report them to me (my role is webmaster with Gian Casalegno for 
the Android app).
The whole transition from the old server need some days while you will 
find www.sundialatlas.net even if you call www.sundialatlas.eu, only for 
few days, anyway nothing changes for the users calling one of the two.


Enjoy it, Fabio

--
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)

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

Re: star-shaped sundial in Finland

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

thanks to all those wrote to me or via the sundial-list.
If there will be other news I will keep you informed.

Thank you, Fabio


Hi all

I've a contact with Susanna Kuokkanen, a student of archeology of the
University of Oulu, Finland.
Oulu is quite close to the polar circle, on the gulf of Botnia.

A star-shaped sundial was found during an axcavation for the
construction of a building in Tornio.
Tornio is just at the top of the gulf, on the border with Sweden.
Susanna sent me the photos of the sundial, you can see the card FI8 in
Sundial Atlas (www.sundialatlas.eu/atlas.php?so=FI8).

It is an equinoctial sundial, star-shaped with 12 points, and another
sundial on its upper surface, without the gnomon.
Susanna was instructed by the university to do a research, later the
sundial will be moved to the Tornio museum.
She hasn't gnomonic notions and she found in Sundial Atlas some
star-shaped sundials and, above all, the menu 'gnomolab' where there are
many models of paper sundials. One of these, the app 7, is a star-shaped
sundial strikling similar with the find of Tornio.
I helped her to build the paper sundial for her latitude and it shows
the same indications.
In the area of Tornio there were many merchants from XVI to XVIII
centuries, it was a rich area for the fur market, and she thinks the
sundial come from another southern area, carried by one of these merchants.

I asked her news about the basement, it'd have clarified the latitudine
of its origin, but it wasn't found.

I'm writing a report for her with explanations how a star-shaped works
but an important point of her research is to understand the origin of
the sundial.
Have you some ideas about the probable provenance ?

thank you, Fabio

--

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)

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







--
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)

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

star-shaped sundial in Finland

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

Hi all

I've a contact with Susanna Kuokkanen, a student of archeology of the 
University of Oulu, Finland.

Oulu is quite close to the polar circle, on the gulf of Botnia.

A star-shaped sundial was found during an axcavation for the 
construction of a building in Tornio.

Tornio is just at the top of the gulf, on the border with Sweden.
Susanna sent me the photos of the sundial, you can see the card FI8 in 
Sundial Atlas (www.sundialatlas.eu/atlas.php?so=FI8).


It is an equinoctial sundial, star-shaped with 12 points, and another 
sundial on its upper surface, without the gnomon.
Susanna was instructed by the university to do a research, later the 
sundial will be moved to the Tornio museum.
She hasn't gnomonic notions and she found in Sundial Atlas some 
star-shaped sundials and, above all, the menu 'gnomolab' where there are 
many models of paper sundials. One of these, the app 7, is a star-shaped 
sundial strikling similar with the find of Tornio.
I helped her to build the paper sundial for her latitude and it shows 
the same indications.
In the area of Tornio there were many merchants from XVI to XVIII 
centuries, it was a rich area for the fur market, and she thinks the 
sundial come from another southern area, carried by one of these merchants.


I asked her news about the basement, it'd have clarified the latitudine 
of its origin, but it wasn't found.


I'm writing a report for her with explanations how a star-shaped works 
but an important point of her research is to understand the origin of 
the sundial.

Have you some ideas about the probable provenance ?

thank you, Fabio

--

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)

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

bellows sundial 2

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

same place, same time, looking at NE, 4 hours to sunset

ciao Fabio

--
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)

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

bellows sundial 1

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

Hi all,

nowhere, looking at NW, 7 hours from sunrise.

ciao Fabio

--
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)

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

Kepler

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

Hi, I just finished  a work that has engaged me in the last two weeks.

For those are interested about the 
Kepler's laws, it

---
New Outlook Express and Windows Live Mail replacement - get it here:
http://www.oeclassic.com/

 is an orrery to show the true anomaly starting from the mean anomaly.

The mathematical formula expresses the mean anomaly as a function of the 
eccentric anomaly, function of the true anomaly (the true anomaly is the angle 
of the vector ray that sweeps out equals areas during equal intervals of time)
The problem is that the first formula is not reversible. There are some 
iterative mathematical methods to get the eccentricity anomaly from the mean 
one, with several steps up to the desidered approximation, or it is possible 
the resolution into an infinite series of terms but not a direct formula.

Here math limps. But what can not be achieved with a formal language can be at 
hand by changing the language, so suggests Godel.
So I designed a gear structure to get the mean anomaly from the eccentric one, 
like the formula, ma the movement of the gears, unlike the formula, can work 
contrariwise.
I attached an image of an orrery, for the moment it is virtual, where turning a 
knob with a costant angular velocity, the mean anomaly, you get the movement of 
a planet on an elliptical orbit, following the Kepler's 
laws.
The turquoise planet follows the true anomaly and the one outside the zodiac 
follows the mean anomaly.
This orrery is setted with an eccentricity of 0.7216, far higher than he 
Earth's one (0.0167086), to point out the gear's dinamic and the elliptical 
movement.
I also upload a video on youtube: https://youtu.be/Y5eSOfd5Imk

This work is the entrance door to calculate the eot with gears instead to use 
the customary cam, this is the target for some future gnomonic projects.

ciao Fabio

Fabio Savian
fabio.sav...@nonvedolora.it
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

sunflower

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

Hi all

I just finished to design an horizontal sundial adjustable for a range of 
latitude, in this case from 30° N to 50° N, I also built it with laser cut 
plywood.
Revolving the sunflower changes the angle of the polar style, the latitude is 
engraved (always by laser) at the base of the sunflower, a green arrow on the 
horizontal dial point out to it.

ciao Fabio



---
New Outlook Express and Windows Live Mail replacement - get it here:
http://www.oeclassic.com/
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: An interesting piece of timekeeping

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

Hi all, the watch shows also sunrise and sunset.
Does it mean one have to set latitude and longitude while he moves ?
For the cost of the watch I think it's improbably to suggest don't leave home.
Probably these kind of wrist watches

---
New Outlook Express and Windows Live Mail replacement - get it here:
http://www.oeclassic.com/



 are a status symbol to show other things, not what means the indications.

ciao Fabio





- Original Message -
From: Willy Leenders 
To: J. Tallman 
Cc: Sundial Mailing List 
Sent: 17/01/2017 13:45:18
Subject: Re: An interesting piece of timekeeping



I do not understand all the indications on this watch.
The illustrated watch indicates that it is September 17th.Then the sun is in 
Virgo. However, the indication of the zodiac sign on the watch is Libra.
Where should I read the equation of time.
Why, moreover, the watch does not indicate directly the solar time?


Simplex veri sigillum. (Simplicity is the hallmark of true)


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-jan-2017, om 03:42 heeft J. Tallman het volgende geschreven:


It is not a sundial, but interesting nonetheless:


http://www.ablogtowatch.com/vacheron-constantin-les-cabinotiers-celestia-
astronomical-grand-complication-3600-watch/


It is quite a feast for the eyes, and the mind...and if you have a spare 
million lying around, it could be yours!



Best, 


Jim Tallman
Artisan Industrials


www.artisanindustrials.com 
www.spectrasundial.com 
jtall...@artisanindustrials.com 
513-253-5497
---
https://lists.uni-koeln.de/mailman/listinfo/sundial
---
https://lists.uni-koeln.de/mailman/listinfo/sundial