Re: Romanian reclining sundial

[Michael Ossipoff]

On Fri, Oct 2, 2015 at 6:12 AM, Willy Leenders 
wrote:

> Dan,
>
> What I mean is this:
>
> 1.
> Together with the sundial on the roof is given the EOT table.
> What can you do with it?
>

Well, you can add the EoT table entry to the time shown on the sundial, to
get standard time.



> As a result of the empirical way of construction on September 1 you can,
> using the EOT table, determine the standard Eastern European Time on
> other days.
>

On any day, yes.

Of course, that's clear from what the original-poster said.


> Specifying the length correction you could also determine the true local
> time
>

Yes, you could get local true solar time by adding or subtracting 4 minutes
to the sundial's reading for each degree of latitude east or west of the
place's time-zone's central meridian.

As for the choice of local true solar time, or true solar time at the
central meridian, both dial-marking systems are frequently, widely, used.
Which you use is a matter of individual preference.

Either you mark the dial for true solar time at the central meridian, or
you incorporate the longitude correction in the EoT table. Both methods are
popular.


>
> 2.
> To indicate the standard Eastern European Time you have many options:
> clock, cell phone, computer ...
> There's no need to a sundial.
>

Sundials have aesthetic value. Though they can often be of practical
time-telling use, that isn't their only justification.

Yes, a sundial marked in true solar time at the central meridian is, by
implication, intended or emphasized for practical use.


> Indicating the true local time is only possible on a sundial.
> Let him do it  !
>

Yes, that's one valid preference, one vaild choice. But both choices are
valid.

Yes, I personally  like a sundial to give local true solar time, and
incorporate the longitude-correction in the EoT table. That's how I made my
pocket-portable tablet-dials.

Nevertheless it must be accepted that not everyone makes the same choice
that we make, and that many sundials are marked in true solar time at the
central meridian.

Michael Ossipoff

On Fri, Oct 2, 2015 at 6:12 AM, Willy Leenders 
wrote:

> Dan,
>
> What I mean is this:
>
> 1.
> Together with the sundial on the roof is given the EOT table.
> What can you do with it?
> As a result of the empirical way of construction on September 1 you can,
> using the EOT table, determine the standard Eastern European Time on
> other days.
> Specifying the length correction you could also determine the true local
> time
>
> 2.
> To indicate the standard Eastern European Time you have many options:
> clock, cell phone, computer ...
> There's no need to a sundial.
> Indicating the true local time is only possible on a sundial.
> Let him do it  !
>
>
> 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 1-okt-2015, om 22:06 heeft Dan-George Uza het volgende geschreven:
>
> Willy,
>
> I'm sorry but I did not quite understand your message. The dial is
> supposed to show standard Eastern European Time, not true local time. The
> longitude correction for Bistrita is already built in the hour marks
> because they were empirically drawn according to the watch when EoT was 0.
> Therefore the correction table only deals with variations in Eot.
>
> Dan
>
> On Thu, Oct 1, 2015 at 10:55 PM, Willy Leenders  > wrote:
>
>> A nice project for the decoration of the roof !
>> However, it is not possible to read the true local time.
>> And one can not deduce it for the place at longitude: 24° 30′ 3.82′′ E
>> (Bistrita) with only the table for EOTas a tool.
>>
>>
>> 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 1-okt-2015, om 21:24 heeft Dan-George Uza het volgende geschreven:
>>
>> Dear group,
>>
>> I am happy to be able to share a picture of the first Romanian reclining
>> sundial built recently by Damaschin Berende, a friend from a neighboring
>> town. It's made of plywood, it sits on a roof and it features both a EoT
>> correction table and interchangeable hour marks for winter time and
>> daylight saving time. Reported accuracy is so far around 1:30 min.
>> Direction of gnomon across the roof was fixed by taking a plumb bob shadow
>> ​reading ​
>> from the base of the gnomon at local noon, the elevation angle was
>> calculated according to the latitudine and the hours were marked on the
>> shadow during September 1st, when EoT was 0. I especially like the wooden
>> pole etched with traditional solar motifs and the rooster on top. You can
>> view more photos here:
>>
>> 

Re: Romanian reclining sundial

[Michael Ossipoff]

On Thu, Oct 1, 2015 at 3:55 PM, Willy Leenders 
wrote:


> A nice project for the decoration of the roof !
>

Yes, but more than a decoration.


> However, it is not possible to read the true local time.
>

Could you explain that statement?

True local time, or true local time at the central-meridian, is what
sundials are marked in.

They used to typically give "temporary hours", but that is no longer their
usual time-system.



> And one can not deduce it for the place at longitude: 24° 30′ 3.82′′ E
> (Bistrita) with only the table for EOTas a tool.
>

If the dial is marked in true-solar-time, as opposed to true-solar-time at
the central meridian, and if the EoT table doesn't incorporate the
longitude-correction, then one could get standard time by adding or
subtracting 4 minutes from the EoT entry, for each degree of longitude west
or east of the place's central meridian.



Michael Ossipoff
26N, 80W

On Sun, Oct 4, 2015 at 7:13 AM, Michael Ossipoff 
wrote:

>
>
> On Thu, Oct 1, 2015 at 3:55 PM, Willy Leenders 
> wrote:
>
>
>> A nice project for the decoration of the roof !
>>
>
> Yes, but more than a decoration.
>
>
>> However, it is not possible to read the true local time.
>>
>
> Could you explain that statement?
>
> True local time, or true local time at the central-meridian, is what
> sundials are marked in.
>
> They used to typically give "temporary hours", but that is no longer their
> usual time-system.
>
>
>
>> And one can not deduce it for the place at longitude: 24° 30′ 3.82′′ E
>> (Bistrita) with only the table for EOTas a tool.
>>
>
> If the dial is marked in true-solar-time, as opposed to true-solar-time at
> the central meridian, and if the EoT table doesn't incorporate the
> longitude-correction, then one could get standard time by adding or
> subtracting 4 minutes from the EoT entry, for each degree of longitude west
> or east of the place's central meridian.
>
>
>
> Michael Ossipoff
> 26N, 80W
>
> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

RE: Romanian reclining sundial

[Jack Aubert]

I agree that it is reasonable design choice to include the longitude 
correction.  In fact, I think I would include longitude correction in anything 
that is not a straight-up north-south or a horizontal dial where the longitude 
correction makes the dial look skewed.  Once the dial is already shifted out of 
a straight-up north-south alignment then the longitude correction doesn’t look 
“funny”.   And at that point, you may as well set it to summer time (AKA 
daylight saving time) since that is in effect for more than half the year 
including the months when people are more likely to be outside looking at a 
sundial.

 

But these are all reasonable design choices where there is plenty of room for 
debate.

 

We (NASS) set up what I call a “nonce dial” a few years ago for an exhibition 
in Washington, DC.  It was adjusted to show local clock time on the day of the 
exhibition incorporating both longitude and EOT for the date… but it was 
designed a few months before the US congress decided to extend daylight saving 
time further into the autumn so it ended up being off by exactly one hour from 
watch time.  We put up a poster that said “Why is your watch wrong?” It was 
interesting to watch the reactions.  Some people immediately knew why; others 
seemed perplexed.  

 

Jack Aubert

 

 

From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Michael 
Ossipoff
Sent: Sunday, October 04, 2015 7:42 AM
To: Willy Leenders; sundial list
Subject: Re: Romanian reclining sundial

 

On Fri, Oct 2, 2015 at 6:12 AM, Willy Leenders  
wrote:

Dan,

 

What I mean is this:

 

1.

Together with the sundial on the roof is given the EOT table.
What can you do with it?

 

Well, you can add the EoT table entry to the time shown on the sundial, to get 
standard time. 

 

As a result of the empirical way of construction on September 1 you can, using 
the EOT table, determine the standard Eastern European Time on other days.

 

On any day, yes.

Of course, that's clear from what the original-poster said.

 

Specifying the length correction you could also determine the true local time

 

Yes, you could get local true solar time by adding or subtracting 4 minutes to 
the sundial's reading for each degree of latitude east or west of the place's 
time-zone's central meridian.

As for the choice of local true solar time, or true solar time at the central 
meridian, both dial-marking systems are frequently, widely, used. Which you use 
is a matter of individual preference.

Either you mark the dial for true solar time at the central meridian, or you 
incorporate the longitude correction in the EoT table. Both methods are popular.
 


2.
To indicate the standard Eastern European Time you have many options: clock, 
cell phone, computer ...

There's no need to a sundial.

 

Sundials have aesthetic value. Though they can often be of practical 
time-telling use, that isn't their only justification.

Yes, a sundial marked in true solar time at the central meridian is, by 
implication, intended or emphasized for practical use.

 

Indicating the true local time is only possible on a sundial.
Let him do it  !

 

Yes, that's one valid preference, one vaild choice. But both choices are valid.

Yes, I personally  like a sundial to give local true solar time, and 
incorporate the longitude-correction in the EoT table. That's how I made my 
pocket-portable tablet-dials.  

Nevertheless it must be accepted that not everyone makes the same choice that 
we make, and that many sundials are marked in true solar time at the central 
meridian.

Michael Ossipoff

 

On Fri, Oct 2, 2015 at 6:12 AM, Willy Leenders  
wrote:

Dan,

 

What I mean is this:

 

1.

Together with the sundial on the roof is given the EOT table.
What can you do with it?

As a result of the empirical way of construction on September 1 you can, using 
the EOT table, determine the standard Eastern European Time on other days.
Specifying the length correction you could also determine the true local time


2.
To indicate the standard Eastern European Time you have many options: clock, 
cell phone, computer ...

There's no need to a sundial.
Indicating the true local time is only possible on a sundial.
Let him do it  !

 

 

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 1-okt-2015, om 22:06 heeft Dan-George Uza het volgende geschreven:





Willy,

 

I'm sorry but I did not quite understand your message. The dial is supposed to 
show standard Eastern European Time, not true local time. The longitude 
correction for Bistrita is already built in the hour marks because they were 
empirically drawn according to the watch when EoT was 0. Therefore the 
correction table only deals with variations in Eot.   

 

Dan

 

On Thu, Oct