Re: Is this an educational sundial, or a 'NON-dial'?

[Kevin Karney via sundial]

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I am not a particular fan of analemmatic dials, but .. for children of the 
right age and ability who are taught by an inspirational teacher, the 
delineation and decoration of an analemmatic dial in the school playground has 
great merit in the amalgamation of history, art, astronomy, trigonometry, 
geometry and practical measurement. 

Kevin Karney, Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales  
Phone 01594 530 595 or 07595 024 960

> On 5 Apr 2021, at 09:09, Siegfried Netzband  
> wrote:
> 
> 
> Hi alll,
> agree in general to everything that has been said about the analemmtic 
> sundial. To me the interactivity is the main advantge of the dial. Especially 
> today. It attracts people to work with it and not just to look at it or even 
> just notice it (or not, because they do not know what a dial is or do not 
> understand "what is going on there").  One thing I miss in the discussion: 
> The bearing stones. To me they make the dial quite interesting - but they 
> very seldom appear in reality and in discussions. By them the dial becomes, 
> without sunshine, a year round sun calender. In literature about the 
> analemmatic dial they are missing quite often. Why is the fact "without 
> sunshine" so seldom taken up and why do so very few dials have these stones? 
> Any idea?
> Regards
> Siegfried
>  
>  
>  
> Siegfried Netzband
> Hebelstr. 12
> 75233 Tiefenbronn
> Tel: 07234 2802
> Fax: 07234 942909
> Mob: 0151 53083636 / 0160 1531634
> E-Mail: siegfried.netzb...@t-online.de
> E-Post: siegfried.netzb...@e-post.de
> Skype: siegfried75233
> www.ferienhaus-frieseneck.de
>  
>  
>  
>  
>  
>  
>  
> -Original-Nachricht-
> Betreff: Re: Is this an educational sundial, or a 'NON-dial'?
> Datum: 2021-04-05T09:37:28+0200
> Von: "Maes, F.W." 
> An: "Jack Aubert" 
>  
>  
>  
> Hi all,
>  
> One property of the analemmatic dial I like to stress: when it has the right 
> size, you can act as gnomon yourself. This makes it an interactive 
> instrument, which is appealing: you have to DO something to get the time. And 
> with the good frame of mind it makes you feel part of the celestial 
> gearworks, which may even be more satisfying.
>  
> Best regards,
> Frans Maes
>  
> 
>   Virusvrij. www.avg.com
> 
>> On Sat, Apr 3, 2021 at 10:28 PM Jack Aubert  wrote:
>> The author’s web site seems to be an attempt to monetize has plans for 
>> analemmatic dials claiming that the whole thing is educational.  There is 
>> even a link for franchised distributors!  I suppose it would be interesting 
>> to see what kind of information is contained in the book.  The drawing on 
>> the cover is, like a stopped watch, occasionally correct – but only once a 
>> day and only if you decide what part of the shadow to use.  It looks like a 
>> scam.
>> 
>>  
>> 
>> My personal view of analemmatic dials is that they can be decorative and 
>> even entertaining, but are not very educational at all.  It is hard enough 
>> for me visualize the projection of a conic section onto a horizontal plane 
>> and relate it to the sky and the sun let alone explain it to a kid.  It’s 
>> somewhere between magic and a trick pool shot.
>> 
>>  
>> 
>> Jack Aubert 
>> 
>>  
>> 
>>  
>> 
>> From: sundial  On Behalf Of R. Hooijenga
>> Sent: Saturday, April 3, 2021 3:47 PM
>> To: sundial@uni-koeln.de
>> Subject: RE: Is this an educational sundial, or a 'NON-dial'?
>> 
>>  
>> 
>> For this kind of instrument, I personally like to use the term 'Undial'.
>> 
>> So far, it didn't catch on, however - pity! 
>> 
>>  
>> 
>> Good Easter,
>> 
>> Rudolf Hooijenga 52 30 N 4 40 E
>> 
>>  
>> 
>> -Oorspronkelijk bericht-
>> 
>> Van: sundial  Namens Linda Reid
>> 
>> Verzonden: zaterdag 3 april 2021 20:04
>> 
>> Aan: sundial@uni-koeln.de
>> 
>> Onderwerp: Is this an educational sundial, or a 'NON-dial'?
>> 
>>  
>> 
>>  
>> 
>> [...]  but looking at the illustration on the front cover, it seems to be a 
>> 'NON-dial'!
>> 
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
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[no subject]

[Kevin Karney via sundial]

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Hi Thibaud,

Python is the BEST language for technical programming (especially during the 
current home lock-down). I have been doing all my gnomonic work on Python for 
some 15 years so I have many gnomonic routines. 

I have :

complete Mees routines for solar position, altitude, azimuth, hr angle, etc

all the conversions you might need (date to JD, JD to y/m/d/h/m/s, decimal hrs 
to hh:mm, etc), 

Solar Az/Alt to x-y position on a planar dial. 

Many EoT routines

All are in stand-alone python 2.x routines so may need minor tweaking to 
upgrade to python 3 (arguments for print statements need to be enclosed in 
brackets). Many of them have graphical output which use a specific python 
package - Apple Mac based Nodebox 1.0 

If you have an iPhone, I have a neat program that gives all the solar 
parameters, EoT, hr angle and count-down to solar noon using the phone’s 
location & time. This could easily be converted to Android is you know how ti 
access Lat/Long

Are you Windows or Mac based?

By the way, Chris Steyaert (copied above) is converting my Spider Dial code to 
work on his python implementation. He knows 100% more about Python than I.

Best wishes
Kevin

p.s. I also have a vast Excel spreadsheet with all the solar parameters in 
6-hourly UTC intervals from year 2000 to 2050, calculated from US Naval 
Observatory's MICA program, which I use to check my routines. You might find 
this useful--- End Message ---
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[no subject]

[Kevin Karney via sundial]

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Dan
What language was the calendar in? That's a first step to get the latitude. 
Was the time of sunrise/sunset by day or by month average?  
Was the time midnight-to-sunrise and midnight-to-sunset equal for each 
measurement?  That would indicate if the calendar was using solar or mean time. 
N.B. in 1783, France was still using solar time (or so I think) while Britain 
had, by then, generally shifted to local mean time - the transition was slow.

An interesting little problem. By 1793, the knowledge of astronomy was very 
advanced in many European countries.

Let me know if you want help with a number-crunch. I have all the necessary 
routines in Python and could try every possible combination with little 
difficulty

Bear wishes
Kevin--- End Message ---
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[no subject]

[Kevin Karney via sundial]

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See
https://www.theguardian.com/news/2019/jan/11/watching-the-sun-not-the-clock-sleep-body-clocks-daylight-saving-time
 


Happy New Year to you all
Kevin--- End Message ---
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[no subject]

[Kevin Karney via sundial]

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Daniel
Thank you for this explanation. What was strange is now clear.
Thank you also for maintaining this wonderful resource for so long!
Best wishes
Kevin

> On 11 Sep 2018, at 10:45, Daniel Roth  wrote:
> 
> Dear All,
> 
> As the list administrator I'm writing to you that the DMARC topic is annoying 
> a lot of mailing list users. Some explanations are given here: 
> https://wiki.list.org/DEV/DMARC
> 
> This sundial mailing list is currently hosted by a Mailman version 2.1.29 
> installation (I have no influence on this).
> 
> Yet, I could not dive into the topic and the implications of changing 
> settings in the Mailman software. Before changing any setting, you as a 
> member of the list would have to check that you are sending to the sundial 
> mailing list from the address with which you have subscribed to the list. You 
> can check this here: https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
> Best regards
> Daniel Roth, sundial mailing list
> 
> 
> Roger schrieb am 11.09.2018 05:31:
> 
>> 
>> We are all frustrated by the overhead on these DMARC wrapped messages. The 
>> emails generally contain valuable information like Kevin Karney’s link. Why 
>> are these massages “not DMARC compliant?” Generally because the sender has 
>> changed their email address. Perhaps they contain hypertext. Perhaps it is 
>> the nanny state insisting on things that restrict freedom  “for your 
>> protection”.  My advice is to seek the content and ignore the overhead. 
>> Check the properties and source for your typical emails. They also have a 
>> lot of similar but hidden overhead. I enjoy the benefits but still “rage, 
>> rage against the fading of the light”*, the enlightenment we all receive 
>> from these postings.
>> 
>> 
>> 
>> Thanks Kevin for sharing such an excellent study on the equation of time. 
>> https://Equation-of-Time.info  with hypertext removed
>> 
>> 
>> 
>> Regards,
>> 
>> Roger Bailey
>> 
>> Walking Shadow Designs
>> 
>> 
>> 
>> *“Do Not Go Gently..” Dylan Thomas
>> 
>> 
>> 
>> 
>> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

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[no subject]

[Kevin Karney via sundial]

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Dear colleagues and friends

I have spent a lot of time over the last few years in front of my computer 
thinking about the Equation of Time. Recently my son asked where all the output 
of my studies resided. At first, I thought I should write a book. But instead I 
acquired a new domain and found that Adobe had a simple package that allows one 
to make a nice looking website with little technical effort.

You can find the website at https://Equation-of-Time.info

It contains three main sections, all copiously illustrated...
The Equation of Time - 8 pages. Here,  see the videos on why the Equation of 
Time looks as it does (under the page ‘The components of the Equation of 
Time’). I am particularly proud of these!
Sundials that are (or can be) Equation corrected - 8 pages
Mechanical Means to Simulate the EoT - 6 pages.

I have been harvesting images of EoT related things for many years, often 
without recording where they came from. So if I have included an image of yours 
and have not attributed it to you, please let me know.

Please do have a look and send comments/additions/corrections/improvements

Best wishes
Kevin Karney - from Wales--- End Message ---
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[no subject]

[Kevin Karney via sundial]

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All Scottish (& English?) lighthouses had a sundial - how else would they set 
their clocks and thus turn on their lights at the correct time!

Here is…
1852 General Order to Scottish Lighthouse Keepers

The Principal Keeper shall go to the Sun-dial, when the sun is shining, and 
shall watch until the shadow touches any hour.

The Assistant shall stand on the balcony, waiting a signal from the Principal. 

The Principal shall then make the signal; on seeing which, the Assistant shall 
immediately set the Clock.

The Principal shall then take a note of the Equation-of-Time engraved on the 
Sun-dial.

He shall afterwards proceed at once to the Lightroom where he shall put the 
timepiece back or forward…

Best wishes
Kevin


> On 12 Jul 2018, at 20:56, Steve Lelievre  
> wrote:
> 
> 
> 
> My recent visit to Shetland took in the recent summer solstice, allowing me 
> to experience for myself how Shetland's summertime sunsets are very late and 
> sunrises are corresponding early. Daylength at the solstice was around 19 
> hours, with (civil) twilight taking up another 3½ hours or so.
> Here is a photo I took of a sundial at the Eshaness Lighthouse (60.489314°N 
> 1.627209°W). Unfortunately it's on private property, so I couldn't get close 
> enough to read the the little plaque. The current lighthouse was completed in 
> 1929 so I guess the dial may be that early too.
> 
> In Shetland the sun doesn't go anywhere near the zenith even at midsummer so 
> I was surprised by the height of the gnomon. It's just asking to be dinged, 
> but Shetlanders are good and gentle folk so there no sign of vandalism; just 
> a bit of rust and corrosion. 
> 
> I wonder why the dial spans only 12 hours? I have seen a number of other 
> dials that only cover 12 hours but I've never really questioned that 
> attribute before. Of course in this case they've stuck the dial where the 
> nearly building obscures the sun late in the day, so evening hours don't 
> really matter. That aside, surely we should expect a dial made for such a 
> northerly location to reflect the extreme summer daylengths? There is plenty 
> of open space nearby where the dial could have been sited to accept sunlight 
> throughout the summer evenings.
> 
> To me it seems a trivial matter to design a dial that covers the full 
> midsummer daylength. Can anyone justify, or at least explain, the 12 hour 
> limit?
> 
> Steve
> 
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

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Re: Missing an opportunity

[Kevin Karney]

John
Not very beautiful, as you say,  by pretty impressive technology - I'll try to 
get to see it. Berkeley Castle is not too far from my home. I'll post some 
photos if I get there.
Kevin


> On 28 Jun 2018, at 16:03, John Goodman  wrote:
> 
> The sundial shown at this link looks completely conventional but it was made 
> out of stainless steel using a 3D printer. Someone at the Renishaw company 
> should have contacted this list to commission a more interesting design!
> 
> http://trends.directindustry.com/project-181814.html 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

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Re: Pocket sundial

[Kevin Karney]

Yes, I have one. It’s nice as a demonstrator - it fulfils all the design 
requirements of such a dial. But it is not precision made…
Kevin

> On 21 Sep 2017, at 08:57, Dan-George Uza  wrote:
> 
> Hello, has anyone got one of those?
> 
> https://www.pocket-sundial.com/ 
> 
> 
> Dan-George
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

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Re: Brass or Bronze for Sundials.

[Kevin Karney]

Hi Roderick
Contrary to John's advice, you do NOT need to cast bronze. You can buy bronze 
sheet in many thicknesses. You will need to go to a specialist metal supplier 
and it is quite expensive. The supplier that I have used for four sundials 
lists 12 different varieties of bronze. I cannot remember which variety I used, 
but I could probably dig it out for you from my files.  

Bronze can  be easily and accurately cut by water jet. (Don't try to cut with a 
hand saw - it is very hard). It can then be photo-etched, which gives beautiful 
results. The only significant issue with the material (like brass) is 
protecting the material from birds until the metal gets naturally patinated. 
This can be done by occasional application of micro-crystalline wax (e.g. 
Renaissance Wax). You can also chemically patinate the surface, but personally, 
I have not found a patinating colour that I like.

I am presently thinking of CNC engraving a bronze dial, but - as yet - have not 
risked the expense of a botched job!

Bronze or Brass bronze is harder to obtain and work but very durable. Brass 
(obtainable in 12 different varieties) is generally a more friendly material to 
work but less durable.

Good luck
Kevin

Sent from my iPad

> On 6 Jun 2017, at 22:35, John Carmichael  wrote:
> 
> Brass is used when you need a metal that can be easily tooled and manipulated 
> (bent, drilled, hammered, cut, engraved and soldered) and is available in 
> many shapes and specialized pieces (rods, strips, tubes, angles, wire, cable, 
> screws, nuts, washers, finials, knobs, etc.). Your hardware store has a wide 
> selection of brass pieces and very little in bronze.   Use brass if you want 
> to construct a sundial that needs these pieces and requires assembly, and if 
> you want to make it yourself.  Bronze is used when a casting is required 
> without much assembly.   It requires an expert to cast it, and it’s 
> expensive. (Like Chris Daniel’s cast bronze dolphin sundial statue in 
> Greenwich)
>  
> There are other arguments for and against each metal, but I think these are 
> the most important ones.  In my own view, The color of the patina is not 
> nearly as important as the other considerations I mentioned, since they both 
> weather well and aren’t damaged by rust.
>  
> Best wishes
>  
>  
> From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of 
> rodwall1...@gmail.com
> Sent: Sunday, June 4, 2017 6:58 PM
> To: sundial@uni-koeln.de
> Subject: Brass or Bronze for Sundials.
>  
> Hi all,
>  
> For a sundial that will be out in the weather. What is the 
> advantage/disadvantage of using brass or bronze?
>  
> Regards,
>  
> Roderick Wall.
>  
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
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Re: Dial face colouration

[Kevin Karney]

Dear Steve

I do not know how you are planning to cut and fabricate your plastic sheeting. 
But if you have not looked,  there are many many bi-colour double layered UV 
resistant acrylics used by the sign-writing industry. See, for example, 
https://www.engraving-supplies.co.uk/laser-materials/trolase.html 
. The 
advantage of these materials (or single colour acrylics) is that they can be 
either cut and engraved with great precision and minimal cost by laser-cutting. 
All you need is a good .pdf graphic made to appropriate specs for your 
laser-cutter. Typically, text - which is raster-engraved - will be one colour. 
While vector lines and curves will be lines of a certain thickness and of 
different colours (one colour for a cut, others for different depths of 
engraving).

One of the great advantages of the laser cut approach is that you can try 
endless designs cut/engraved on cardboard - costing virtually nothing, before 
committing to your more expensive final material.

Laser cutting is cheap these days and if you live anywhere near a big city, you 
may find that there is a 'FabLab', where you can go and do it yourself - see 
www.fablabs.io/labs/map 

Having started designing sundials by laser-cutting in Cardiff University's 
FabLab - I am now actually employed there part-time to teach others in 
laser-cutting. So I am happy to elucidate further if anyone is interested.

cheers
Kevin

> On 24 Feb 2017, at 18:04, Steve Lelievre  
> wrote:
> 
> Fellow sundiallers,
> 
> I’m planning to make my next sundial from outdoor grade UV resistant plastic 
> sheeting. These come in a range of colours and I want to choose one that 
> works well for a sundial. Assuming I get the material grit-blasted or somehow 
> treated so that it not shiny, and leaving aesthetic considerations aside, 
> what light-related attributes should I be looking for?
> 
> As anyone who has played with paper sundials knows, a white surface is hard 
> to look at in full sun, even if non-shiny; black would not show any shadow. I 
> need something in between: light enough to catch a shadow, but dark enough to 
> avoid glare in full sun. I assume that latitude has a bearing on this, as the 
> midday sun illuminates more strongly as we approach the equator. In my case, 
> the design latitude is around 45 N. My dial will be about 25cm in diameter.
> 
> Are there any conventions or empirical guidelines, or even practical 
> experience, to help me choose?
> 
> Which properties matter? I quick read of Wikipedia suggests colours seem to 
> involve hue, saturation or luminosity (or parallel concepts in other 
> classifications).
> 
> Cheers,
> Steve
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

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Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Kevin Karney]

Hi Ken
I you want to observe how the Equation of Time varies over the years, go to my 
website
http://www.precisedirections.co.uk/Sundials/index.html

The second item may be of interest to you. It gives a table of EoTs (including 
the longitude correction for your time zone). And you can choose either a 
single year or a four year cycle.
For the four-year cycle, the average local noon EoT is calculated for each 
calendar date, except 29 Feb, which stands on its own. If you want the EoT 
without the longitude correction, set your longitude to your time zone 
longitude.

The calculations used are far more rigorous than needed for gnomonic purposes. 
They use the complete VSOP theory as described by Meeus and the EoT is 
topographical rather than geocentric (which only makes a marginal difference). 
If you use browser (like Chrome) which allows you to see the web-page source, 
you can see the calculations involved. (In Chrome, select View>Developer>View 
Source)
EoTs calculated have an accuracy of +/- .06 secs of time - using US Naval 
Observatory's MICA program as standard.
I think it is interesting to see how the 4-year table changes as one jumps 4 
years into the future...  

See the first item on the original page for comments on the calculations
and consider using a "Victorian EOT" table which gives all the information 
needed but in a tenth of the space

The Latitude/Longitude finder - using Google Earth is a bit ratty, but seems to 
work for Elizabethtown.

Let me know if you have any problems.

Best wishes
Kevin


> On 26 Jan 2017, at 00:21, Kenneth R clark  wrote:
> 
> I had an error message from AOL Sorry for no subject line and my files were 
> not sent.
> Let me retry with this account.
> 
> Hi everyone,
> 
>  I am working on my Equation of Time plaque for my aluminum cross 
> sundial.  All the instructions and graphics and EQT will be on an 8 ½” 
> diameter ½” aluminum plate.  I do not want to use the standard graph found on 
> many sundials but instead a chart for the whole year, mins and secs, to add 
> or subtract total correction to get watch time.  I do not have much room for 
> detailed instructions.
> 
>  I looked at difference sources for the chart and would like to verify 
> the most accurate times to use the four year leap year cycle for a church at 
> 40.1526N, 76.6038W.   I have looked at the Solar Noon calculator, Sonne and 
> Shadows-(cannot input decimal degrees?)  Are there other sources or 
> spreadsheet programs?
> 
>  I like to convey that sundials are accurate.  I envision that a person 
> will wait till the shadow is on a line and the person will know what time it 
> is suppose to be even though this type of sundial may not be design for 
> precision.
> 
>  I made a quick drawing.  There will be some type of sun image at the top 
> and a logo at the bottom for the location.  The chart in the center is from 
> another project that I did just to see how it would look and if the printing 
> is large enough to read.  I would have to change the inputs to standard time 
> for the whole year.  I have also attached a picture of the sundial.
> 
>  I just want to know if I am using the right times and would appreciate 
> any comments or suggestions.
> 
> Thanks very much
> 
> Ken Clark 
>   
> 
> Elizabethtown, PA
> ---
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> 
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Re: Permanent DST

[Kevin Karney]

Nothing much changes!
UK Daylight Saving Bill - 1909
William Churchill, President of the Board of Trade
… this Bill does not propose a change from Natural Time to Artificial Time, but 
only to substitute a convenient standard of Artificial Time for an inconvenient 
standard of Artificial Time …
Kevin


> On 19 Nov. 2016, at 23:40, John Pickard  wrote:
> 
> Good morning from sunny Sydney,
> 
> If you think that Europe has a problem with DST, you should try Australia 
> which can only be described as a dog's breakfast. Queensland steadfastly 
> refuses to go on DST because the extra couple of hours of daylight fades the 
> curtains. Although we have a nominal three time zones (AEST, ACST, AWST) 
> there are a couple of towns / villages with times artificially set to be 
> outside the zones they live in. This was originally for commercial reasons, 
> making it easier to do business in adjoining states. These days, such changes 
> are pointless and unnecessary with the internet, but seem to be retained for 
> no particular reason other than to be different. On top of this is DST in 
> various states. As a consequence in summer you can meet more than five 
> different times in Australia which means that on a long trip you can spend a 
> lot of time changing the clocks in cameras, etc.
> 
> Most of us in the southern states like DST (regardless of its effect on our 
> curtains!) and look forward to it at the end of winter. Equally, we don't 
> like when it ends.
> 
> Of course the funniest thing about DST are the arguments of opponents who 
> seem to think that the 24 hour clock is some immutable thing handed down from 
> the gods, rather than a convenient human construct. And if you change the 
> time, then the world as we all know it will come to a shuddering end. These 
> people simply don't understand that the only thing that changes is the "time" 
> you get out of bed. Although I mostly work from 0700 to 1800 or thereabouts, 
> I have done fieldwork in Antarctica and Patagonia where we changed to later 
> starts and finishes because of the extreme winds in the morning. Why start at 
> 0700 and get hammered by wind all morning when you can start at 1200 (when 
> the wind has died down), and work the same number of hours through the 
> afternoon and evening relatively wind-free? So we had breakfast at 1100, hit 
> the ice at 1200 and worked through until about 2200 with almost no wind. Of 
> course, this is only really feasible in high latitudes in summer with very 
> extended daylight hours. But it does show that "time" as shown on a clock 
> face is often irrelevant.
> 
> 
> Cheers, John
> 
> John Pickard
> john.pick...@bigpond.com
> 
> -Original Message- From: Isabella McFedries
> Sent: Saturday, November 19, 2016 4:02 PM
> To: sundial@uni-koeln.de
> Subject: Re: Permanent DST
> 
> In message 
> 
> Dan-George Uza  wrote:
> 
>> Dear group,
>> 
>> We are witnessing a few interesting developments! After Turkey decided a
>> few months ago to remain on Daylight Saving Time all year round, Hungary is
>> now considering to do the same.
>> 
>> http://www.seattletimes.com/nation-world/hungary-mulls-staying-on-daylight-saving-time-all-year-round/
>> 
>> If the measure passes, neighboring countries Hungary and Romania will share
>> the same official time for half of the year although they are located in
>> different time zones (CET and EET respectively). For eastern Hungary the
>> sun sets at about 15:40 during winter, i.e more than an hour ahead of
>> Paris, which shares its time zone.
>> 
>> I'm wondering: aren't EU member states supposed to equally follow DST by
>> law?
>> 
>> 
>> Dan Uza
> 
> 
> Hi, Dan
> 
> You are PARTLY correct - but (as I understand it), all EU member countries
> must CHANGE their clocks on the SAME date, although they still keep their
> individual Time-zones.  For example, UK and Ireland are on GMT, whereas
> France/Germany are on CET, and countries such as Greece on CET + 1 hour.
> 
> There are other examples of locations which are on PERMANENT 'Daylight
> Saving' time - for example here in Canada, the province of Saskatchewan
> should really be in the 'Mountain' zone (GMT-7), but always STAYS in the
> 'Central' zone (GMT-6) and so does NOT change its clocks twice a year.
> 
> I am afraid that these things are always for the Politicians to decide!
> 
> 
> Sincerely,
> 
> Isabella McFedries.
> 
> 
> -- 
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

---
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Re: STONE SUNDIAL

[Kevin Karney]

Oops - misread for Mike Cowan

Sent from my iPad

> On 4 Nov 2016, at 08:08, Frank King <f...@cl.cam.ac.uk> wrote:
> 
> Kevin Karney wrote:
> 
> Dennis,
> 
> Your nearest port of call would be the
> geology department at the Sedgwick museum
> in Cambridge...
> 
> Many readers will find this a little puzzling
> given that Dennis lives but a stone's throw
> from The Cockburn Geological Museum at the
> University of Edinburgh whereas Cambridge is
> over 300 miles further away.
> 
> The clue lies in the sign-off...
> 
> Kevoin
> 
> The superfluous "o" indicates that he was
> using a stereographic projection and, by
> assumption, Edinburgh was the pole of the
> projection.
> 
> Frank
> 
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial

Sent from my iPad

> On 4 Nov 2016, at 08:08, Frank King <f...@cl.cam.ac.uk> wrote:
> 
> Kevin Karney wrote:
> 
> Dennis,
> 
> Your nearest port of call would be the
> geology department at the Sedgwick museum
> in Cambridge...
> 
> Many readers will find this a little puzzling
> given that Dennis lives but a stone's throw
> from The Cockburn Geological Museum at the
> University of Edinburgh whereas Cambridge is
> over 300 miles further away.
> 
> The clue lies in the sign-off...
> 
> Kevoin
> 
> The superfluous "o" indicates that he was
> using a stereographic projection and, by
> assumption, Edinburgh was the pole of the
> projection.
> 
> Frank
> 
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: STONE SUNDIAL

[Kevin Karney]

Dennis,
Your nearest port of call would be the geology department at the Sedgwick 
museum in Cambridge. Check with Frank if he knows any sundial friendly staff 
there
Kevoin

Sent from my iPad

> On 2 Nov 2016, at 09:51, Mike Isaacs  wrote:
> 
> Re Stonehenge.
> 
> In current Private eye No 1430.
> 
> 
> In message <7c83e361e13f474abba83a78450c8...@smtp-cloud6.xs4all.net>, Thibaud 
> Taudin Chabot  writes
>> How was it done with the stones of Stonehenge?
>> 
>> At 21:09 1-11-2016, Dennis Cowan wrote:
>> Does anyone know of a facility in the UK where a piece of stone
>> from a sundial can be sent to try to establish where the stone
>> originated from?
>> 
>> Dennis Cowan
>> 
>> Sent from my Mobile
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>> 
>> Th. Taudin Chabot, . tcha...@dds.nl
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>> 
> 
> -- 
> Mike Isaacs
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
---
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Re: Longcase Clock with Equation of TIme

[Kevin Karney]

As explained by Fred Sawyer in a recent lecture to the British Sundial Society, 
if often worked the other way around... people had an equation table and all 
kinds of rules so that they could adjust their clock so that it matched dial 
time for as long as possible. 

Dial time was (and still is for some) 'true' time. The acceptance of local mean 
time was a slow process. Likewise the acceptance of national mean time met with 
a great deal of resistance. In Dorchester in 1858, in the UK, a judge in a 
court case found in favour of the plaintiff, since the defendant was not 
present at 10:00 o'clock when the case was scheduled. The court was using GMT. 
The defendant arrived at 10:00 local mean time - a few minutes late. He 
appealed and the appeal judge ruled...
"Ten o’clock is 10 o’clock according to the Time of the Place and the Town 
Council cannot say that it is not, 
but that it is 10 o’clock by Greenwich 
time. Nor can the time be altered by a railway company.… Nor by any person who 
regulates the clock on the Town-Hall."

Unless you lived in a (maritime) city, or had an astronomer on hand, or a local 
rich man who went up to the city and owned a chronometer, there was NO way to 
set a clock without a Sundial. It all changed with the the arrival of the 
telegraph   I have found that this is something that watch and clock 
enthusiasts sometimes forget!

Kevin

Sent from my iPad

> On 7 Oct 2016, at 11:07, rodwall1...@gmail.com  wrote:
> 
> Hi all,
> 
> In 1730. I think I heard somewhere that. Clock manufacturers also sometimes 
> gave a small window sundial to allow you to set your clock. With a equation 
> of time table. Is that correct?
> 
> Roderick Wall..
> 
> 
> - Reply message -
> From: "Robert Terwilliger" 
> To: "'Ian Maddocks'" , "'Sundial list'" 
> 
> Subject: Longcase Clock with Equation of TIme
> Date: Fri, Oct 7, 2016 1:00 PM
> 
> If you had a similar clock in 1730 - located where you didn't have access to
> another accurate clock, a sundial would be the only way you could set it -
> and to do so you would need to know the equation for the date. 
> 
>  
> 
> Bob
> 
>  
> 
>   _  
> 
> From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Ian
> Maddocks
> Sent: Wednesday, October 5, 2016 12:29 PM
> To: Sundial list
> Subject: Longcase Clock with Equation of TIme
> 
>  
> 
> hi folks
> 
>  
> 
> I was just blundering around the internet when I came across the following
> that may be of interest..
> 
>  
> 
> A long case clock from 1730 London that has an annual dial for displaying
> the date and the equation of time
> 
> http://www.raffetyclocks.com/antique-clocks/d/antique-month-equation-and-yea
> r-calendar-longcase-clock-by-john-topping-london/170271
> 
> It's a premade disk with EoT table that rotates in a year, not a P type
> kidney cam, but was new clock complication to me
> 
>  
> 
> greetings from 
> 
>  
> 
> Ian Maddocks
> Chester, UK
> 53°11'50"N  2°52'41"W
> frog.happy.froze
> 
>  
> 
>  
> 
>  
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Spider Dials

[Kevin Karney]

Dear Gnomonists

Recently, there has been a small correspondence about Spider Dials. This 
message mainly concerns those who like to do all their gnomonic calculations 
programatically.

I attach a short text file that contains the routines needed to prepare spider 
curves for a horizontal dial with a gnomon of given thickness. Computer 
routines are usually language and implementation specific (as these are), but 
the logic and gnomonics provided are correct (or so I hope and pray). The 
language is Python, which is easily read and quite easily adaptable to any 
other language (e.g. Java).

For me, the advantage of using a programical approach is that I use the same 
program to prepare graphics files that can be sent to...
i) a laser engraver to make a cheap plywood maquette of my design to check 
things out
ii) a water jet cutting company to cut out the dial plate and gnomon
iii) a photo-etching company to create the dial.

I am current working on the routines to generate G-Code that can go direct to a 
CNC routing engraver. I would love to hear from anyone working on a similar 
approach.

Best wishes
Kevin

p.s anyone who wants the astronomical routines mentioned in the text file have 
only to ask!


# Here are two routines that I use to draw Spider Hour lines on horizontal 
dials.
# They are written in Python, which is easy to read and can be adapted to 
# any other language quite simply

# Items such as Latitude, Time Zone etc are prefixed by My_ . These are global 
variables
# The coordinate sysyem is x-axis East/West, y-axis North/South downwards

def Get_Point(Year,Month,Day,Hour,Minute,Second,The_radius):
# This routine is for a horizontal dial with a gnomon of given 
thickness 
# It returns an x-y coordinate of the intersection of...
#   a gnomon's shadow line 
#   a circle centred in the middle of the dial
# Inputs are the Date and CIVIL Time and the radius of the circle

# The routine calls Sunpos - a general purpose astronomical support 
routine 
# based on the rigorous algorithms of Meeus' "Astronomical Algorithms", 
# which provides (amongst other things) the Sun's True Hour Angle.
# (the routines use temperature, pressure and height - far beyond the 
accuracy
# requirements of this application, but computers calculate quickly 
these days)

Result= Sunpos(My_Latitude_deg, My_Longitude_deg, 
My_Time_Zone,My_DST,
   Year, Month, Day, Hour,  Minute, Second,
   My_Temp,My_Press,My_Height)

#=
# Sunpos returns...
# 0 RA_hrs
# 1 Decl_deg
# 2 Radius_Vector_AU
# 3 EoT_Gnomon_Min
# 4 GMST_hrs
# 5 Alt_deg
# 6 Azim_deg
# 7 LHA_deg
# 8 Sunrise_hrs
# 9 Sunset_hrs
# unpack the variable of the Result that I need
HA_deg= Result[7]
HA_rad= radians(abs(HA_deg))

# Calculate the Hour Line Angle
HLA_rad   = atan(tan(HA_rad) * sin(radians(abs(My_Latitude_deg
if (HA_deg > 90 or HA_deg < -90) : HLA_rad = HLA_rad + pi
HLA_deg   = degrees(HLA_rad)
 
# My_Noon_Gap is the thickness of the gnomon, HNG = Half Noon Gap
HNG = My_Noon_Gap/2. if (HLA_deg < -90 or HLA_deg > 90) else 
-My_Noon_Gap/2. 
 
# Signer picks the correct of the two intersection points between line 
and circle
Signer = 1 if HLA_deg < 90 else -1

# this part just does the coordinate geometry to find the intersection 
of line with circle
tanGamma = tan(HLA_rad)
dd = My_Style_Foot_Posn * tanGamma - HNG
aaa = 1 + tanGamma**2
bbb = 2 * dd * tanGamma
ccc = dd * dd - The_radius ** 2
y1 = (-bbb + Signer * sqrt(bbb**2 - 4 * aaa * ccc)) / (2 * aaa)
x1 = sqrt(The_radius**2 - y1**2)

# Switch sets the x-coordinate depend whether morning or afternoon 
Switch = 1 if HA_deg > 0 else (-1 if HA_deg < 0 else 0)
if HA_deg <> 0. :
xxx = Switch * x1
yyy = - y1 #  graphics system has +ve y down the screen
else: # deals with Noon
xxx = HNG
yyy = -sqrt(The_radius**2 - HNG**2)
return (xxx,yyy)

def Do_Spiders():
# The routine calls two general purpose routines
# Julian_Day - which gives to the Julian Day Number for a given 
Year/MonthDay
# Get_Date_Time_from_JD - which Year/Month/Day from a given Julian Date

# The Loop to draw ALL of the Spider Lines
# The_Civil_Mins is the time on your watch
The_Civil_Mins = int(60 * My_Start_Hour) # an integer
The_End_Minutes= int(60 * My_End_Hour)   # an 

Fwd: Looking for a sundial 'twin': wide gnomon spider - second try with smaller photo NUMBER 2

[Kevin Karney]

> Begin forwarded message:
> 
> From: Kevin Karney <kar...@me.com>
> Subject: Re: Looking for a sundial 'twin': wide gnomon spider - second try 
> with smaller photo NUMBER 2
> Date: 26 May 2016 at 17:50:46 BST
> To: Helmut Haase <helmut.ha...@teleos-web.de>
> 
> 
>> On 23 May 2016, at 18:54, Helmut Haase <helmut.ha...@teleos-web.de 
>> <mailto:helmut.ha...@teleos-web.de>> wrote:
>> 
>> Hi,
>> I have designed and realized a horizontal spider sundial with polar pointing 
>> wide gnomon, see details below and photo (in a second approach sadly reduced 
>> to 47 kB now). Does anyone know such a sundial anywhere else? I found many 
>> spider sundials but none with a wide polar gnomon. A photo link or any other 
>> information would be great?

---
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Re: Looking for a sundial 'twin': wide gnomon spider - second try with smaller photo

[Kevin Karney]

Dear Helmut

I have made such a dial for a friend in 5mm bronze, (so its gnomon is 5mm 
wide). It was cut with a water-jet (cost £250) and photo etched (cost £210). It 
contains sunrise and sunset lines. Somewhat similar to yours as far as density 
of hour lines etc, but somewhat smaller. 

The design was accomplished entirely from Python code (more than 2000 lines of 
code - a lot of which are the very precise astronomical algorithms). I made a 
number of laser-engraved/cut maquettes from 5mm plywood (about £10 each) to get 
the final design approved by my friend's children who paid the bill.  The 
software produced 3 different images - one for there laser-cutter, one for the 
water-jet cutter and one for the photo-etchers. 
Now I can produce a design similar to this one at any other Lat/Long in a very 
short time.

I'll send you other pictures by separate e-mail

The only other dial of this type I know in in the Parkes Observatory in New 
South Wales, Australia. You can find one image of it with a Goggle search 
"Parkes Observatory sundial"

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595


> On 23 May 2016, at 18:54, Helmut Haase <helmut.ha...@teleos-web.de> wrote:
> 
> Hi,
> I have designed and realized a horizontal spider sundial with polar pointing 
> wide gnomon, see details below and photo (in a second approach sadly reduced 
> to 47 kB now). Does anyone know such a sundial anywhere else? I found many 
> spider sundials but none with a wide polar gnomon. A photo link or any other 
> information would be great?

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

Re: 3D digital sundial

[Kevin Karney]

Bill
I've used OpenScad. It does what it says on the box. But with a steep learning 
curve - unless you are familiar with programmical modelling - it's all a matter 
of creating a primitive shape, scaling it, rotating it, moving it and then 
adding or subtracting from what you have created before. The programming 
language is java-like and rather cumbersome. I include a little picture of an 
early prototype of the 3D-printered interior shell of a dodecahedral sundial. 
(The dial faces will be laser engraved on thin plywood and stuck onto the 
shell). Also the OpenScad code to produce this shape.
Give it a try!
Kevin




Height   = 100 ;// millimeters
Arm_Thickness= 5 ;
Ply_Thickness= 2.6;
Wall_Thickness_Below_Ply = 3;
Look_Inside  = 1; // ENTER 1 TO CUT THE MODEL IN HALF

// *
//  D E F I N E   T H E   D O D E C A H E D R O N   A N D   P E N T A G O N  
// *
module dodecahedron(height) {scale([height,height,height])
{intersection()
{cube([2,2,1], center = true); 
intersection_for(i=[0:4]) 
{rotate([0,0,72*i]) rotate([2 * atan((1 + 
sqrt(5))/2.),0,0])cube([2,2,1], center = true); 

module pentagon(x_rad,thickn)
{difference() // Carve 3 sides off a Cylinder
{cylinder(r=x_rad,h=thickn+.001);
for ( i = [0 : 4] ) {rotate([0,0,72.*i  ]) translate([x_rad,0,0]) 

cube([x_rad,1.5*x_rad,1.5*x_rad], center = true); }}}

// *
// C A L C U L A T E   V A R I O U S   P A R A M E T E R S 
// *
Gold_Rat= (1 + sqrt(5))/2.;   // Golden Ratio
Dihedral= 2 * atan(Gold_Rat); // Dihedral; Angle
Pentagon_Size   = Height/Gold_Rat  - Arm_Thickness;
Inner_Dimension = Height - 2 * (Ply_Thickness + Wall_Thickness_Below_Ply);

// *
// B U I L D   T H E   M O D E L
// *
difference() {
// Make Dodecahedron hollow
difference(){dodecahedron(Height); dodecahedron(Inner_Dimension);}
// Remove Pentagons fron Top & Bottom Faces
rotate([0,  0,18]) translate([0,0,Inner_Dimension]) 
pentagon(Pentagon_Size,Ply_Thickness);   // Top Face
rotate([0,180,18]) translate([0,0,Inner_Dimension]) 
pentagon(Pentagon_Size,Ply_Thickness); // Bottom Face
// Remove Pentagons fron Upper Side Faces
for ( i = [0 : 4] ) {rotate([0,180-Dihedral,90+ i*72 ]) 
rotate([0,0,36]) translate([0,0,Height/2 - Ply_Thickness]) 
pentagon(Pentagon_Size,Ply_Thickness);}
// Remove Pentagons fron Lower Side Faces
for ( i = [0 : 4] ) {rotate([0,Dihedral,90+36 + i*72 ]) 
rotate([0,0,0 ]) translate([0,0,Height/2 - Ply_Thickness]) 
pentagon(Pentagon_Size,Ply_Thickness);}
// Cut Model in half if desired
if (Look_Inside)
{translate([-Height,-Height,-0]) cube(2*Height);} }



> On 6 Nov 2015, at 14:15, Bill Gottesman  wrote:
> 
> Very cool.  Has anyone had a chance to try the free 3D software OpenScad?  By 
> the way, I am skeptical that the sundial can handle declinations near the 
> solstices.
> -Bill
> 
> On Fri, Nov 6, 2015 at 7:39 AM, Darek Oczki  > wrote:
> Hello everyone
> 
> Have you seen this 3D digital sundial?
> http://3dprint.com/103289/open-source-3d-print-sundial/ 
> 
> 
> --
> Best regards
> Darek Oczki
> 52N 21E
> Warsaw, Poland
> GNOMONIKA.pl
> Sundials in Poland
> http://gnomonika.pl 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial 
> 
> 
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

---
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Re: largest sundial

[Kevin Karney]

Come now everyone! Tall buildings, dams No! The largest dial in the world 
is undoubtedly in Tasmania. Initial construction was fine but somehow the hour 
lines were never inscribed.
Google Dial Range Tasmania and find the images of Mount Dial & Mount Gnomon.
Best wishes
Kevin


> On 27 Oct 2015, at 19:04, R.Pauli  wrote:
> 
> I heard Bill Nye The Science Guy talk about his father wanting to set out 
> marks for the Washington Monument.   
> Great idea, but the problem was the fuzzy shadow.   
> 
> 
> On 10/27/2015 3:33 AM, Jackie Jones wrote:
>> Can someone please tell me what is the world’s largest sundial?   If a 
>> vertical tower, how high above the ground is the nodus?  I have been 
>> consulted by someone who is claiming that a tower he wants to use as a 
>> sundial, which is 162m tall, will be the world’s largest dial.  There are 
>> many issues with a dial of this size, which will be explained to him, but I 
>> would like to know about sizes of other large dials, please.  This is not 
>> just a tall building casting a shadow, but one where there are hour markings 
>> on the ground.
>>  
>> With best wishes to you all,
>> Jackie
>>  
>> Jackie Jones
>> 50° 50’ 09” N0° 07’ 40” W
>>  
>> 
>> 
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial 
>> 
>> 
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial 
> 
> 

---
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Re: Temporal Hours

[Kevin Karney]

I think this is a really important thread !

My interest in this whole subject is the various client populations (whose 
who needed to tell the time) and what technologies they employed and what 
accuracies they achieved

I think one can easily see five (sometimes overlapping) populations…
The astronomers and astrologers who undoubtedly used and understood mean hours 
(one only has to read Ptolemy’s 150AD ‘Almagest' to understand the depth of 
understanding of the ancient astronomers. This class of person had the 
capabilities to make the Antikythera mechanism and would have had the wit to 
try polar dials. It’s my guess that all those exceptional examples of early 
non-scaphe/hemispherium/etc dials could be attributed to this client 
population.  (And one needs to remember that most astronomers were astrologers 
(e.g Ptolemy) - there was nothing quaint about that subject from ancient days 
through to the Enlightenment.)
The civic authorities who need to announce the time so that city gates could be 
opened, markets started etc. These were the people who provided all those 
beautiful Greek and Roman type dials that sat on pillars or in easily visible 
public places. To this group, one can perhaps add the very rich - there is a 
beautiful little personal sundial from Pompei
The religious authorities - who generally wanted control - ref Pope Sabianus’ 
encyclical (606 AD) on mass dials, which was preceded by St Augustine’s 5th C 
definition of the Christian prayer times (which was derived from ideas from 
some earlier saint - whose name I can’t remember - who was the first to declare 
that prayers should be said on time). All of the 8 prayer times - except Vigil 
in the middle of the night - was defined by the Sun (dawn, sun-rise etc). Then 
along came Islam and their 5 prayer times initially mirrored those of the 
Christians (Fajr = Lauds, Zuhr = Sext, Asr = Nones, Maghreb = Vespers, Isha = 
Compline). This client population used... 
Christians - Mass dials were used in the countryside by the church until the 
Enlightenment. In towns, they would used mass dials  until clocks came along 
for the cathedrals and rich monasteries/churches. Beda tables were also used by 
the church
Muslims - personal shadow length (until the introduction of normal common hours 
dials - starting with the Ibn el Shatir dial). Of interest is the fact that 
Muslim purists still refer to variants of the original personal shadow length 
rules to dictate their prayer times.
Ordinary people who used their personal shadow length to tell the time using 
Beda tables - what were available across Europe for various latitudes until 
medieval times. Thereafter they would use publicly visible sundials or clocks. 
There was not much change in this until clocks became available to the middle 
classes in 17/18th C and to the poor in the 19th/20th C.
Rich people - always ahead of the game. They would use the handsome and 
beautiful miniature dials of the late medieval and renaissance times, until 
clocks and eventually watches (both of which were expensive) began to be more 
widely made.

And then there was the Clepsydra… The simple ones were good for telling “How 
Long” and were very commonly used. The complex ones which told “When” were 
developed by the Greeks (e.g. Ctesibius in 245 BC) and made glorious by the 
Chinese (Su Sung 1088), the Arabs (al Sa’ati 11xx) and Persians (Al Jazari 
1206). But these were the domain of the city fathers or the very, very 
wealthy/powerful. As far as I know, the first sophisticated water clock to 
reach Europe was a gift from the King of Persia to Charlemagne ca 900AD. 
Ctesibus’ clock had gearing to allow it to tell the time in unequal hours. As 
far as I can see, Su Sung’s  al Saati's and Al Jazari's clock told the time in 
Common Hours (but I would need to research further to be sure of this). I found 
a quote that Ctesibus was more accurate than any clock until the arrival of the 
pendulum (I wonder if this a really true!)

And what about accuracy of the “When in the day. Until the arrival of the 
Huygens’ pendulum clock (1656), one would be lucky to tell the time from a 
clock to better than +/-15 mins - sundials perhaps doing rather better. Serious 
time telling by clocks with minute or second accuracy was only really required 
to meet demands of navigators and then the growth of science and industry 
leading to the industrial revolution. And always bear in mind that until the 
arrival of the telegraph and railways, no one in the countryside could set a 
clock with anything other than a sundial (except perhaps unless they were an 
astronomer).

Does anyone know of an authoritative and available source on water clocks?

Kevin


 On 3 Aug 2015, at 02:55, Jack Aubert j...@chezaubert.net wrote:
 
 I assume that you are referring to the Arachne of the Amphiareion.  I have a 
 photocopy of your article on that dial, which was reconstructed from 
 fragments, describing a (very old) horizontal dial with equal 

Re: A translucent sundial

[Kevin Karney]

Chi-Liang
It's magnificent! Well done...
Kevin

Kevin Karney
Freedom Cottage, Llandogo, Monmouth, NP25 4TP
Phone 01594 539 595. Mobile 07595 024 960
---
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Re: hemi truncated icosahedron

[Kevin Karney]

Fabio
Quite brilliant ! That is a tour-de-force in programming.
Best
Kevin

Kevin Karney, MA JP
Freedom Cottage, Llandogo, Monmouth NP25 4TP.
Phone 01594 530 595 Mobile 07595 024 960

 On 19 Jun 2015, at 22:44, Fabio nonvedolora fabio.sav...@nonvedolora.it 
 wrote:
 
 Hi all
  
 I’ve just finished a new paper sundial, it is available as app 41, 
 www.sundialatlas.eu/atlas.php?app=41 
 http://www.sundialatlas.eu/atlas.php?app=41
  
 It is like an hemi-sphere but realized with an half truncated icosahedron.
 To simulate the sphere I used this archimedean solid, also known as 
 fullerene, with 32 faces: 12 pentagons and 20 hexagons.
 It is also rendered with the image of the Earth (image credit of NASA – 
 Goddard Space Flight Center)
  
 Setted any coordinates, the app turns the solid so that the correspondent 
 point becomes the lower point, on the vertical axis trough the center of the 
 solid, then it dissects the solid with an horizontal plane to get the pseudo 
 hemisphere.
 The app returns a pdf of 3 pages. The 1st with the section, the 2nd with the 
 development of the half solid and the 3th with the basement and the gnomon.
  
 The edge of the gnomon reaches the center of the solid and shows the time in 
 the concave pseudo hemi-sphere where  there are also drawn the hour lines.
 The edge of the shadow shows the time but also the point on the Earth where, 
 moment by moment, the Sun is at zenith.
  
 The algorithm is quite complex, the time to get the pdf may be about 18 
 seconds (server time) for half analemma every hour to about 72 seconds for 
 the whole analemma every 5 minutes (not very useful). A common case of half 
 analemma every 10 minutes require about 30 seconds.
  
 Important note: the browsers have embedded a pdf reader to show these files 
 but they are not very accurate. May be you see lines slightly out of position 
 or you don’t get printed the dotted lines. The solution is very simple, save 
 the pdf in your computer, then open the file with Acrobat Reader, it is fully 
 able to show and print the whole content.
  
 On the top face you can also read the amplitude and the daylight arc.
  
 I verified the app with many locations, everything seems ok but your reports 
 will be welcome.
  
 Enjoy the summer solstice on app 41, ciao Fabio
  
 hemi-truncated-icosahedron[1].jpg
  
 Fabio Savian
 fabio.sav...@nonvedolora.it
 www.nonvedolora.eu
 Paderno Dugnano, Milano, Italy
 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2)
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A Sundial in a family crest and coat of arms

[Kevin Karney]

I met  nice man with surname Hyndman who was proud that he had a sundial in his 
family crest and motto. See attached.
The motto is part of a poem dated 1662 by Samuel Butler called Hudibras

Their duty never was defeated,
Nor from their oaths and faith retreated;
For loyalty is still the same,
Whether it win or lose the game;
True as the dial to the sun,
Although it be not shin'd upon.

The words are from Samuel Butler’s satirical poem Hudibras (line 175) dated ca 
1663. The last two lines can be seen on a sundial on the south wall of St John 
the Baptist, Halifax, which is dated 1808.



Best wishes
Kevin---
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Re: 3D printing

[Kevin Karney]

Dear Friends

For anyone interested to try out 3D printing, laser cutting, CNC routing etc, I 
suggest you see if you have a FabLab anywhere near you. There are hundreds 
around the world and they are springing up all the time. FabLab is the 
brainchild of MIT

Fab Lab is the educational outreach component of MIT’s Center for Bits and 
Atoms (CBA), an extension of its research into digital fabrication and 
computation. A Fab Lab is a technical prototyping platform for innovation and 
invention, providing stimulus for local entrepreneurship. A Fab Lab is also a 
platform for learning and innovation: a place to play, to create, to learn, to 
mentor, to invent. To be a Fab Lab means connecting to a global community of 
learners, educators, technologists, researchers, makers and innovators- -a 
knowledge sharing network that spans 30 countries and 24 time zones. Because 
all Fab Labs share common tools and processes, the program is building a global 
network, a distributed laboratory for research and invention.
See http://www.fabfoundation.org/fab-labs/ 
http://www.fabfoundation.org/fab-labs/ for the location of the labs.

I have (for a modest fee) joined the FabLab in Cardiff - and am having LOTS OF 
FUN. The Lab is attached to the Art  Design department of the University 
(which gives access to lots of brainy switched-on youngsters AND I am once 
again a paid-up student - which brings all kinds of student discounts). Any 
time I want, I can go there and use their software (they have everything - 
including Solidworks) - and, having designed what I want, their computers are 
connected to about 10 3-D printers, 2 Laser cutters a massive 2D CNC router. To 
use the equipment, you pay a small half-hourly charge.

You can see my first gnomonic attempt at 
http://www.fablabcardiff.com/projects/capuchin-sundial/ 
http://www.fablabcardiff.com/projects/capuchin-sundial/  

I am now busy designing a 3D icosahedral dial - in miniature! It will be just 
some 12 cm high, The icosahedral shell and stand will be 3D printed using 20 
micron fused filament Ultimaker. Each face of the icosahedron will have a 1 mm 
depression -  into which the 20 triangular dial faces will be embedded. Each 
face will be laser etched/cut into 1mm thick wood. I have not worked out how to 
do the gnomons yet!

I could do the whole thing on the 3D printer - but this way I can avoid the 
complexities of precise geometry 3D modelling of the dial faces - and replace 
it with the easy 2D design. The laser etching and cutting is lightening fast 
and cheap so I can afford to make plenty of mistakes along the way.

John - if you are toying with buying a 3-D printer, have a look at 
http://printrbot.com/compare-printers/ http://printrbot.com/compare-printers/ 
A student in Cardiff has built one of their $349 models and it looks really 
neat and it works a treat! Be aware that there is plenty of free 3D modelling 
software. (e.g. Blender, openScad, kokopelli) and their output matches all the 
industry standards.

Have fun
Kevin


Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595


 On 5 Dec 2014, at 13:30, Tony Moss tonylindi...@talktalk.net wrote:
 
 Hi all,
  I mentioned the possibility of making elaborate pierced gnomons 
 using 3D printing in a very recent article in BSS Bulletin but I never 
 expected the real possibility to be so near at hand.  Using plastic printed 
 'patterns' from which to cast e.g. bronze gnomons would probably result in a 
 non-rigid result as cast metal is usually quite soft.  I wonder if we will 
 ever be able to print particulate metals in 3D which could then be 
 'sintered'.  This process is rather like baking a cake but using metal 
 ingredients to make rigid components.
 
 No doubt I will probably now find that facts have overtaken this thought 
 already. :-(
 
 Tony Moss
 
 
 
 -Original Message-
 From: Simon \[illustratingshadows via sundial sundial@uni-koeln.de 
 mailto:sundial@uni-koeln.de
 To: John Pickard john.pick...@bigpond.com 
 mailto:john.pick...@bigpond.com; Sundial List sundial@uni-koeln.de 
 mailto:sundial@uni-koeln.de
 Sent: Fri, 5 Dec 2014 1:54
 
 Attached Message
 From: Simon [illustratingshadows illustratingshad...@yahoo.com 
 mailto:illustratingshad...@yahoo.com
 To:   John Pickard john.pick...@bigpond.com 
 mailto:john.pick...@bigpond.com; Sundial List sundial@uni-koeln.de 
 mailto:sundial@uni-koeln.de
 Subject:  Re: 3D printers - PS an ooops
 Date: Fri, 5 Dec 2014 01:53:26 + (UTC)
 ooops  ~ the pictures I attached were for the dial without longitude 
 correction, sorry. Not relevant to the issue at hand, namely the key point 
 was the use of the .STL file type and suffix. US printer prices are similar 
 to those in Australia I think, I imagine other printer vendors may use a file 
 type other than .STL however their software should spell out what their 
 printer needs.
 
 Simon
 
 
 
 Simon Wheaton

Re: Fabio's Sundial Smile

[Kevin Karney]

Thanks, Mario! I now know what my grandchildren's first sundial will look 
like
Kevin

Kevin Karney
Freedom Cottage, Llandogo, Monmouth, NP25 4TP
Phone 01594 539 595. Mobile 07595 024 960

 On 14 Nov 2014, at 23:00, Mario Arnaldi marna...@libero.it wrote:
 
 If you like smiles, I give you my the man on the moon :-)
 Mario
 
 
 ---
 Questa e-mail è priva di virus e malware perché è attiva la protezione avast! 
 Antivirus.
 http://www.avast.com
 the man on the moon.jpg
 ---
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Re: Acronychal rising

[Kevin Karney]

Hi Marcello

To find when the sun is in opposition to a star, you must work with the Righty 
Ascension. All our time measurements relate to the rotation of the earth about 
the equator.
The equation for opposition is RA_sun = RA_star -12 hrs
but RA_sun = GMST - UTC - EoT +12 (all in hours)
thus GMST = RA_Star + UTC + EoT
and GMST = 6.6973374558 (Sun's HA at Greenwich at Epoch 2000) + 24 / 365.242191 
* D_0:00 (days  from Epoch 2000 to UTC midnight) + 366.24219 / 365.242191 * 
UTC_Hrs_since_midnight + minor precessional constant 

(Epoch 2000 is noon UTC on 1 Jan 2000, EoT is the strict astronomical 
definition = minus that commonly used by gnomonists)

With a bit of graph plotting and iteration, you can solve these two equations 
to get the moment of opposition in terms of Date  UTC

If you want all details of all the basic theory, see 
http://www.precisedirections.co.uk/Sundials/
There is a document there called  Basic Solar Positional Astronomy

Best wishes
Kevin

On 23 Sep 2014, at 14:51, Marcelo mmanil...@gmail.com wrote:

 Hi fellows!
 Could you please solve this little doubt of mine: I’m intending to
 make a cylindrical “bottle” sundial, which would show the acronychal
 rising of some stars. But, how can I calculate the nearest day when
 the perfect opposition between the sun and a given star occurs? I
 mean, what’s the best way to define it? When there are 12 sidereal
 hours of difference between their right ascensions, or when their
 ecliptic longitudes have a difference of 180°? I’ve tried both
 methods, and found that they can produce a difference as great as 6
 days between results.
 ---
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CORRECTIONS Extensions to A few new Tables for the Gnomonist...

[Kevin Karney]

Dear Friends

Thanks for the positive comments!
And thanks to Gianni Ferrari, Patrick Powers, Edward French and Jack Aubert for 
pointing out the MAJOR error in the Annual Equation of Time Table. 
It was giving EoT values across the table instead of down, which is an error I 
had corrected before - but had crept back in!
That has been corrected Many apologies

Also, by popular request,  I have changed the sign of EoT from the strict 
astronomical convention to the more usual gnomonical convention (the correction 
to get from sundial to local mean time).

Gianni also wants Azimuth measured from the South... I am a 0 deg at North 
person. Any thoughts ? I will probably change things to give a radio button, so 
you can choose.

I have had requests for a solar noon table and solar east/west table and a 
half-minute Victorian table - which I shall implement in due course

Best wishes
Kevin
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Re: CORRECTIONS Extensions to A few new Tables for the Gnomonist...

[Kevin Karney]

Thanks, Patrick
That glitch has been fixed.
Kevin

On 12 Jun 2014, at 21:38, Patrick Powers patrick_pow...@compuserve.com wrote:

 Hi Kevin,
 Thanks for that change.  An apparently similar problem seems to apply to the 
 ‘Victorian EoT’ table when Longitude is zero.  There are then listed EoT 
 values of 23 and 24 mins in Jan and Feb.
  
 You asked for input re formats on azimuth.  I think that just as with the 
 sign of the EoT there are conventions that grew up with gnomonics and 
 conventions that arose within astronomy and navigation.  If what you are 
 providing is intended more as a resource for those interested in sundials 
 then maybe Gianni’s view should prevail?
 I suspect your idea of a radio button for these would be the best option!
 Regards
 
 Patrick
  
 From: Kevin Karney
 Sent: Thursday, June 12, 2014 6:12 PM
 To: Sundial
 Subject: CORRECTIONS  Extensions to A few new Tables for the Gnomonist...
  
 Dear Friends
  
 Thanks for the positive comments!
 And thanks to Gianni Ferrari, Patrick Powers, Edward French and Jack Aubert 
 for pointing out the MAJOR error in the Annual Equation of Time Table.
 It was giving EoT values across the table instead of down, which is an error 
 I had corrected before - but had crept back in!
 That has been corrected Many apologies
  
 Also, by popular request,  I have changed the sign of EoT from the strict 
 astronomical convention to the more usual gnomonical convention (the 
 correction to get from sundial to local mean time).
  
 Gianni also wants Azimuth measured from the South... I am a 0 deg at North 
 person. Any thoughts ? I will probably change things to give a radio button, 
 so you can choose.
  
 I have had requests for a solar noon table and solar east/west table and a 
 half-minute Victorian table - which I shall implement in due course
  
 Best wishes
 Kevin
 
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A few new Tables for the Gnomonist...

[Kevin Karney]

Dear Friends

I have been amusing myself with the astronomy of the Sun and have done a very 
complete coding of Meeus' routines for finding EoT, altitudes, azimuths, etc, 
etc. These deal with precession, nutation, aberration, parallax and the 
differences between TT, UT1 and UTC time.  This has yielded routines of much 
greater precision than are generally required by the gnomonist. However the 
speed of computers is such that lengthly routines are hardly noticed. So I have 
produced a javascipt routine and used it to prepare 4 tables for my website. 
They may be of interest to the dialist.

1) For a given civil time and location - all the usual solar parameters are 
calculated (nothing much new here - other than the precision)
2) A table giving the noon Equation of Time and Longitude Correction over any 
given year and location.
3) A list table of civil - v - solar time, altitude, azimuth, declination and 
local hour angle - for any starting date and time, covering any increment of 
seconds. (Useful if you are trying to set a dial and waiting for the Sun to 
shine)
4) An EoT table of the kind used on many old sundials, where the date is given 
every time the EoT changes by 1 minute. (Try changing the year from one to the 
next and see the change due to the leap aye cycle)

You can find these at
http://www.precisedirections.co.uk/Sundials/

Any comments, corrections, suggestions for additional tables or facilities 
would be welcome.
The input of latitude, longitude is a bit basic, but it is hoped to improve on 
this. Also, I plan to produce sunrise/solar noon/sunset tables.
If you use a browser that allows you to view a web-page's source (such as 
Chrome or Firefox), you can see the astronomical routine that is used.

Enjoy!

Best wishes
Kevin
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Re: Planetarium app

[Kevin Karney]

David
Attached is a list of the 1000 brightest stars. If you want more you can get 
lists by constellation from \
http://www.alcyone.de/brightest_stars.html


On 22 May 2014, at 08:56, Astrovisuals m...@astrovisuals.com.au wrote:

 I wonder if anyone can help? I want to produce a basic planetarium app for 
 iPad that shows the appearance of the Night Sky anywhere on earth.
 I believe I need:
 A program to convert RA and Dec to Alt-azimuth co-ordinates.
 A list of stars, plus details about how to add “constellation lines” between 
 selected bright stars.
 A way of incorporating the Milky Way as a vector file.
 Would be grateful for any help; am happy to pay for programs, lists etc.
  
 And on a different subject, I would like to enter a sundial in the Italian 
 Astronomers’ International contest for sundial makers, but cannot find the 
 form to fill in. Can someone supply a PDF or web address?
 Thanks,
 David Widdowson, Astrovisuals Australia
 www.astrovisuals.com.au
 ---
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Re: The GPS zero meridian club

[Kevin Karney]

Shame on you all - abandon this ill conceived club!! The Sun was not involved 
in the conception of WGS84. You should all be expelled from the Sundial mailing 
list as heretics

Kevin Karney
Freedom Cottage, Llandogo, Monmouth, NP25 4TP
Phone 01594 539 595. Mobile 07595 024 960

 On 1 May 2014, at 20:26, Thibaud Taudin Chabot tcha...@dds.nl wrote:
 
 There is an android app called GPS averaging that can average many readings 
 in order to get a more realistic value of the position.
 Thibaud
 
 At 10:44 1-5-2014, Frank Evans wrote:
 Greetings, fellow dialists,
 Ian Maddocks asks what dials are on whole number lat/long lines.
 During the BSS tour of Austria in 2002 we visited a pillar dial labelled 
 Nieder osterreich which claimed to be exactly at 48 deg N, 15 deg. E. It 
 is recorded in   Austria 2002; a sundial safari. Bulletin of the British 
 Sundial Society, 14, 3, 104-109, 2002 with the following: But following 
 the Royal Society's motto Nulius in verba (don't believe a word of it) 
 our party produced several GPS  machines and the monument' position was 
 found to be a couple of thou. out. The suggestion that there were enough of 
 us present to shift it to the correct location was reluctantly rejected.
 Frank 55N 1W.
 
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Re: Calculating the Equation of Time ..

[Kevin Karney]

Bob

Many thanks

The amazement produced by the method I used was the accuracy obtained by JUST 
SIX parameters. That came from an old-fashioned single body Keplerian approach 
that just requires the longitude at perihelion + eccentricity to get the Sun’s 
longitude. Add to that the obliquity to to give RA  Declination. Add to that 
RA at Epoch + length of tropical year + one precessional constant to find the 
connection between UT and GMST.

In truth, if you look at the code in detail - you will see that I had to 
incorporate three simple linear expressions to account for the time variation 
of obliquity, eccentricity and perihelion to get my target accuracy over a 50 
year period (the limit imposed by my use of MICA as ‘accuracy referee’). So 
sensu stricto, you are probably right that I have used more parameters.

Best wishes
Kevin


On 24 Feb 2014, at 02:03, Robert Kellogg rkell...@comcast.net wrote:

 Kevin,
 
 Welcome the the wonderful world of celestial mechanics ... you need to have 
 only six orbital parameters plus time epoch plus earth inclination and 
 sidereal spin, so total of 8 parameters are required 
 
 Bob
 
 On 2/23/2014 6:49 PM, sundial-requ...@uni-koeln.de wrote:
 Send sundial mailing list submissions to
  sundial@uni-koeln.de
 
 To subscribe or unsubscribe via the World Wide Web, visit
  https://lists.uni-koeln.de/mailman/listinfo/sundial
 or, via email, send a message with subject or body 'help' to
  sundial-requ...@uni-koeln.de
 
 You can reach the person managing the list at
  sundial-ow...@uni-koeln.de
 
 When replying, please edit your Subject line so it is more specific
 than Re: Contents of sundial digest...
 
 
 Today's Topics:
 
1. Calculating the Equation of Time and other Solar Parameters
   (Kevin Karney)
2. CORRECTION Calculating the Equation of Time and other Solar
   Parameters (Kevin Karney)
3. Re: Calculating the Equation of Time and other Solar
   Parameters (Bill Gottesman)
4. online manuscript by Mayall and Mayall (Schechner, Sara)
5. Re: Calculating the Equation of Time and other Solar
   Parameters (Roger Bailey)
 
 
 --
 
 Message: 1
 Date: Sun, 23 Feb 2014 19:32:37 +
 From: Kevin Karney kar...@me.com
 To: sundial@uni-koeln.de List sundial@uni-koeln.de
 Subject: Calculating the Equation of Time and other Solar Parameters
 Message-ID: d9c80f35-d4a1-4414-bac3-d1074c51c...@me.com
 Content-Type: text/plain; charset=windows-1252
 
 Dear Friends
 
 I have spend many happy hours during this wet, wet winter investigating and 
 learning how to calculate all the solar parameters that a gnomonist might 
 possibly need  - Equation of Time, Declination, RA, Altitude, Azimuth, Time 
 of Sunset/Rise, etc, etc.
 
 I have been surprised to find that - with traditional calculation methods 
 and an absolute minimum of astronomical information -  it is possible to 
 calculate everything from first principles to a surprising degree of 
 accuracy.
 
 Other than location and local time, only six pieces of astronomical 
 information are required - obliquity, eccentricity, Sun?s GHA at 1/1/2000, 
 longitude of perihelion, a single precessional constant and the length of 
 the tropical year. Accuracies for the EOT are +/- 2 seconds of time For 
 altitudes/azimuths, less than 1 minute of arc - much better than needed by 
 most gnomonic problems.
 
 If any of you are interested in such calculations, I have loaded a document 
 with all the astronomical theory and background plus the code onto my website
 www.precisedirections.co.uk/sundials
 The code is written in Python, a language available on every type of 
 computer, which is very easily understood, quite easily learnt and very 
 easily translated into any other coding language you might like.
 
 If you own an iPad or iPhone, and are prepared to buy a cheap little app 
 called Pythonista, the code will extract locational  time information from 
 your phone - so you do not even have to input this to get your calculations 
 done
 
 You might also like to see a graphic of a civil mean time horizontal dial, 
 which I think is called a hectomoros dial,  that is destined for my garden. 
 This is also on the website.
 
 Enjoy
 Kevin
 -- next part --
 An HTML attachment was scrubbed...
 URL: 
 https://lists.uni-koeln.de/mailman/private/sundial/attachments/20140223/b50a01bb/attachment-0001.html
 
 --
 
 Message: 2
 Date: Sun, 23 Feb 2014 20:06:51 +
 From: Kevin Karney kar...@me.com
 To: sundial@uni-koeln.de List sundial@uni-koeln.de
 Subject: CORRECTION Calculating the Equation of Time and other Solar
  Parameters
 Message-ID: dc4a7b4d-7d8f-4a83-97b9-c2ed7732c...@me.com
 Content-Type: text/plain; charset=windows-1252
 
 My website is ?
 http://www.precisedirections.co.uk/Sundials
 with a capital S for Sundial
 
 Sorry
 K
 -- next part

Calculating the Equation of Time and other Solar Parameters

[Kevin Karney]

Dear Friends

I have spend many happy hours during this wet, wet winter investigating and 
learning how to calculate all the solar parameters that a gnomonist might 
possibly need  - Equation of Time, Declination, RA, Altitude, Azimuth, Time of 
Sunset/Rise, etc, etc.

I have been surprised to find that - with traditional calculation methods and 
an absolute minimum of astronomical information -  it is possible to calculate 
everything from first principles to a surprising degree of accuracy. 

Other than location and local time, only six pieces of astronomical information 
are required - obliquity, eccentricity, Sun’s GHA at 1/1/2000, longitude of 
perihelion, a single precessional constant and the length of the tropical year. 
Accuracies for the EOT are +/- 2 seconds of time For altitudes/azimuths, less 
than 1 minute of arc - much better than needed by most gnomonic problems.

If any of you are interested in such calculations, I have loaded a document 
with all the astronomical theory and background plus the code onto my website
www.precisedirections.co.uk/sundials
The code is written in Python, a language available on every type of computer, 
which is very easily understood, quite easily learnt and very easily translated 
into any other coding language you might like.

If you own an iPad or iPhone, and are prepared to buy a cheap little app called 
Pythonista, the code will extract locational  time information from your phone 
- so you do not even have to input this to get your calculations done

You might also like to see a graphic of a civil mean time horizontal dial, 
which I think is called a hectomoros dial,  that is destined for my garden. 
This is also on the website.

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

CORRECTION Calculating the Equation of Time and other Solar Parameters

[Kevin Karney]

My website is …
http://www.precisedirections.co.uk/Sundials
with a capital S for Sundial

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

Re: a 3d printer printed sundial

[Kevin Karney]

Simon
Fantastic - I wondered who would be first with this technology!

Interestingly, there is a €650 hobby build-your-own 3D printer coming on the 
market from Belgium : working area 20cm*20cm*20cm. Complete with free driver 
software (but I think you need to be able to make the 3D model first in a 
package such as Blender - also free). You can find it by goggling Velleman 
K8200. 

With difficulty, I am trying to find the financial justification for that kind 
of expenditure….. The aim would be to print a miniature one of those magical 
multifaceted Scottish dials of the 17th C.

Best wishes
Kevin


On 3 Jul 2013, at 21:14, maillis...@optusnet.com.au wrote:

 HI Simon,
  
 Thanks for your details on how you printed your sundial. I hope all goes well 
 for your wedding. Please do post some photos of your sundial weeding cake.
  
 Regards,
  
 Roderick Wall.
  
  
 From: Simon [illustratingshadows
 Sent: ‎Thursday‎, ‎July‎ ‎4‎, ‎2013 ‎3‎:‎11‎ ‎AM
 To: Willy Leenders
 Cc: sundial@uni-koeln.de
  
 One of the lessons I have learned over the years is that a single picture or 
 a short paragraph, all possess generalizations, distortions, deletions, 
 suppositions, and other communication errors. And My short paragraph and 
 simple picture contain all of those!
 
 The dial is a prototype, an experiment with 3d printing to learn weaknesses 
 and strengths. The very thin noon line certainly suggests the am and pm hour 
 lines were not offset for gnomon thickness. In fact, the am and pm lines were 
 offset for the gnomon thickness, and the final error between final engraved 
 hour line angle and calculated hour line angle were all less than one degree, 
 except for 1700 and 0700 which was around 2 degrees. It was not an aspect 
 ratio error given the errors are non progressive, so I am looking into that. 
 Using three CAD systems from initial design to final print image will 
 introduce opportunities for errors of tolerance, I imagine. The thin noon 
 line is clearly incorrect, but intentionally so. The dial is not longitude 
 corrected (small, portable thus only correct for latitude, my personal 
 choice) hence noon is obvious, and the thin noon line is part of my 
 experiment in how thin a line I can practically generate in 3d and have it be 
 strong. Similarly, the 0700 and 1700 lines are thick, and the ones in between 
 noon and those extremes, are of varying thickness. Not a mistake, but me 
 playing with the different methods of drafting a 3d line, this technique uses 
 facets on the line, those facets have drawbacks and maybe benefits, I am not 
 a structural engineer. Yes, there are other methods of producing a 3d line, 
 all targets of future fun and experimentation.
 
 There are better ways of doing all of this, however my desire is to stimulate 
 thought, see what is or is not practical, and so on. The use of a 3d printed 
 model for a mold adds other issues; for example were I to use a mold from a 
 3d printer then slip casting then the gnomon design in particular needs 
 significant tapering, and the faceted hour lines would also present an issue. 
 And so on. Of course I can 3d print a mold which is very easy once the dial 
 itself is designed. 
 
 Finally, I am getting married in just over two weeks and I will have this 
 decoration on the wedding cake. Assuming I don't drop it first!
 
 Simon
 
 
  
 Simon Wheaton-Smith
 www.illustratingshadows.com
 Phoenix, Arizona, W112.1 N33.5
 From: Willy Leenders willy.leend...@telenet.be
 To: Simon [illustratingshadows illustratingshad...@yahoo.com 
 Cc: sundial@uni-koeln.de sundial@uni-koeln.de 
 Sent: Wednesday, July 3, 2013 5:40 AM
 Subject: Re: a 3d printer printed sundial
 
 Miraculous technology!
 
 But as always man remains responsible for the result.
 So even for the mistake in this 3D printer printed sundial.
 The 3D printer can apparently not build a thin style, hence the respectable 
 thickness of the style.
 This requires a split - which is not made ​​here - of the hour lines in an 
 eastern and western half, separated by a space as wide as the thickness of 
 the style.
 
 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 3-jul-2013, om 06:38 heeft Simon [illustratingshadows het volgende 
 geschreven:
 
 Here is the second 3d printer printed sundial, lat 33.5, no longitude 
 correction. This is printed using the same material as lego bricks. It is one 
 print run, so the gnomon is integral to the rest of the dial, so no assembly. 
 
 Simon
  
 Simon Wheaton-Smith
 www.illustratingshadows.com
 Phoenix, Arizona, W112.1 N33.5
 From: Simon [illustratingshadows illustratingshad...@yahoo.com
 To: sundial@uni-koeln.de sundial@uni-koeln.de 
 Sent: Wednesday, June 26, 2013 11:14 AM
 Subject: a 3d printer printed sundial
 
 Being stuck at home a lot (still getting over 

Re: Sundial finish

[Kevin Karney]

Dear Art
Sundials Australia by Margaret Folkard  John Ward (available via 
www.sundialsaustralia.com.au) has an interesting chapter on this subject
Best wishes
Kevin Karney

On 6 Jun 2013, at 19:49, Art Krenzel phoenix98...@msn.com wrote:

 There have been several discussions on the optimum shape of a gnomon to 
 produce a good shadow however I have not seen any discussion on the optimum 
 surface coating of a sundial yet.
  
 From the collective experience of this listserve, what surface (color, 
 texture, finish, material, etc) is the best choice to show a gnomon shadow?
 
 Art Krenzel
 
  
 
 
 
 
  
 
 
 ---
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Re: Man Wants heliochronometer

[Kevin Karney]

That is an Aten Sundial made by J. D. Gard 
http://atensundials.com
Sadly Mr Gard has died and I do not know if the business has been continued by 
his wife. The website invites e-mail enquiries and no longer gives prices.

These dials are latitude adjustable, correctable for longitude and summer time 
hours. They are meant for permanent installation so no do have levelling screws 
or compass. There is no my knowledge any heliochronometer that will tell the 
time better than 30 seconds accuracy, but I would love to be corrected on that!

Best regards
Kevin
On 23 May 2013, at 16:26, John Carmichael jlcarmich...@comcast.net wrote:

 This man wrote to me wanting to order a particular type of heliochronometer.  
 I told him that I do not manufacture what he wants and that I would forward 
 his resquest to The Sundial List.  Perhaps one of you can sell him what he 
 wants.  See his description and photo below.
  
 Thx
  
 John
  
  
 From: ja.humb...@bluewin.ch [mailto:ja.humb...@bluewin.ch] 
 Sent: Wednesday, May 22, 2013 4:11 PM
 To: jlcarmich...@comcast.net
 Subject: Accurate heliochronometer
  
 Hello,
 You do what I like!
 I am looking for a very accurate portable heliochronometer that can tell the 
 time to the second in brass, no wood you know why! Shape more or less like 
 picture, but with large Vernier scale, graduated latitude dial in half 
 degrees around ca lat. 30 and 60, size 30-40 cm dial ring diameter, base 
 plate with leveling screw for horizontal setting, compass in the base, 
 precise and large analemma for equation of time, engraved hours and minutes 
 on the ring if possible, motto and figurine on it. My position : lat. 46°31 
 minute N/long. 6°38 minute 50 sec. E.
 How about the price ?
 Best regards,
 Jacques Humbert
 Av. de Rumine 11
 1005 Lausanne/CH
   
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Re: Re quicklime

[Kevin Karney]

Jack
Lime-Mortar should 'fizz' violently with 5%  Hydrochloric Acid (which, of 
course, you will have a bottle of in your garage). Portland cement may 'fizz' a 
bit, depending on how much calcareous matter is in the sand used. You should 
also be able to scotch lime mortar with a copper coin.
Cheers
Kevin

On 15 May 2013, at 01:03, Jack Aubert j...@chezaubert.net wrote:

 This is all fascinating stuff and I will either impress or bore people  with 
 my bogus erudition on the subject.
  
 But Is there an easy way to distinguish lime mortar from Portland cement 
 mortar, like with one’s thumbnail?  In America, the oldest brick buildings on 
 the East Coast are from the mid 18th century but they would generally have 
 been re-pointed with Portland cement.  Last weekend I was checking mortar 
 joints in Alexandria, Virginia, where the oldest buildings date from that 
 period.  They all seemed to have the same sandy consistency.  I jokingly told 
 a homeowners that I was the “mortar inspector”.  He replied “Finally!  We’ve 
 been waiting forever!”  
  
 Jack
  
 From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Kevin Karney
 Sent: Monday, May 06, 2013 2:39 PM
 To: Sundial
 Subject: Re: Re quicklime
  
 A further point about lime mortar. It sets quite hard within a few weeks, but 
 continues to get harder  harder at an exponentially slower rate until the 
 carbon dioxide (as carbonic acid) in the atmosphere eventually converts it 
 back to its original calcium carbonate. So Roman mortar is very very hard and 
 totally inflexible…. Yes!,  it can take thousands of years to re-convert - 
 this is one of the reasons why ancient buildings (as Roman aqueducts) last so 
 long. The conversion is quicker in cold climates since frost makes micro 
 cracks which allows the carbonic acid to percolate into the mortar.
  
 CaCO3 (limestone) ---heat--- CaO (quicklime)+ CO2
 CaO (quicklime)+ H20 --- Ca(OH)2 (slaked lime)
 CO2 + H2O --- in the atmosphere --- H2CO3 (carbonic acid - very weak)
 Ca(OH)2 (slaked lime) + H2CO3 + O2  time --- CaCO3 (limestone) + 2H20
 My chemistry is very rusty - so I hope the formulae are right
  
 All the best 
 Kevin
  
 On 6 May 2013, at 15:32, Frank Evans frankev...@zooplankton.co.uk wrote:
 
 
 Greetings, fellow dialists,
 I'm now clearer on the subject of lime production. After firing It seems the 
 quicklime was taken from the kiln in lumps, separated from the ash and moved 
 to a pit in the nearby slaking shed (cheaper than iron pots). The pit was 
 lined to hold water and the quicklime was (cautiously!) added. It was in 
 timer bailed out and sieved (large lumps might not be completely slaked and 
 could blister later as mortar, with damaging consequences. The resulting 
 slaked lime could now be safely transported. Each firing produced several 
 tons of lime and this was sometimes left to mature for many weeks.
 
 Thanks to all who replied. I hope to talk further on the subject with the 
 stonemason when he returns to Tynemouth in the summer to paint the dial. I 
 note he was careful to chose the correct colour of sand to mix with his lime 
 putty for the repairs.
 Frank 55N 1W
 ---
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 -- 
 This message has been scanned for viruses and 
 dangerous content by MailScanner, and is 
 believed to be clean.
 
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Re: Re quicklime

[Kevin Karney]

A further point about lime mortar. It sets quite hard within a few weeks, but 
continues to get harder  harder at an exponentially slower rate until the 
carbon dioxide (as carbonic acid) in the atmosphere eventually converts it back 
to its original calcium carbonate. So Roman mortar is very very hard and 
totally inflexible…. Yes!,  it can take thousands of years to re-convert - this 
is one of the reasons why ancient buildings (as Roman aqueducts) last so long. 
The conversion is quicker in cold climates since frost makes micro cracks which 
allows the carbonic acid to percolate into the mortar.

CaCO3 (limestone) ---heat--- CaO (quicklime)+ CO2
CaO (quicklime)+ H20 --- Ca(OH)2 (slaked lime)
CO2 + H2O --- in the atmosphere --- H2CO3 (carbonic acid - very weak)
Ca(OH)2 (slaked lime) + H2CO3 + O2  time --- CaCO3 (limestone) + 2H20
My chemistry is very rusty - so I hope the formulae are right

All the best 
Kevin

On 6 May 2013, at 15:32, Frank Evans frankev...@zooplankton.co.uk wrote:

 Greetings, fellow dialists,
 I'm now clearer on the subject of lime production. After firing It seems the 
 quicklime was taken from the kiln in lumps, separated from the ash and moved 
 to a pit in the nearby slaking shed (cheaper than iron pots). The pit was 
 lined to hold water and the quicklime was (cautiously!) added. It was in 
 timer bailed out and sieved (large lumps might not be completely slaked and 
 could blister later as mortar, with damaging consequences. The resulting 
 slaked lime could now be safely transported. Each firing produced several 
 tons of lime and this was sometimes left to mature for many weeks.
 
 Thanks to all who replied. I hope to talk further on the subject with the 
 stonemason when he returns to Tynemouth in the summer to paint the dial. I 
 note he was careful to chose the correct colour of sand to mix with his lime 
 putty for the repairs.
 Frank 55N 1W
 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial
 

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Re: A prize for the worst 'non-dial', of the year?

[Kevin Karney]

Looks like an OK sundial to me. If the latitude is right, it should work…
Every member of NASS  BSS should own one….
Kevin

On 3 Apr 2013, at 21:25, David Andersson davey.anders...@gmail.com wrote:

 
 Dear All,
 
 Can anyone give me information on the attached photograph - such as is it
 a genuine (but useless!) sun-watch, or if the whole picture is a 'spoof'?
 
 A 'body-building' friend sent it to me, today - he says it came from the
 website  http://forum.bodybuilding.com/showthread.php?t=152225673page=179
 
 
 Instead of the Sawyer Dialling Prize (at NASS) - maybe this item could
 be awarded to the worst 'non-dial' design, which appears during the year!
 
 If it is a genuine commercially-available item, I might buy one as a joke.
 
 
 Regards,
 
 David Andersson.
 
 
 -- 
 
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Re: sundials collection in Nuremberg

[Kevin Karney]

Hi Chris
There is a nice book the Ivory Sundials of Nuremberg, 1500 - 1700 by Penelope 
Gouk, ISBN 0 906271 03 7, published by the Whipple Museum of the history of 
Science.

You can I think buy it in theNuremberg Museum, if not from Abebooks.com

Best wishes
Kevin Karney

On 2 Apr 2013, at 12:36, prze...@fizyka.umk.pl wrote:

 Hello  All,
 I am new list-user from Poland.
 
 Do you know of sundials collection in Nuremberg, Germany (Nürnberg)?
 I wonder if it is a part of Germanisches Nationalmuseum or rather an 
 independent institution?
 Is it open for visitors?
 
 Best regards,
 Chris (Krzysztof Przegietka, Torun, Poland; prze...@fizyka.umk.pl)
 
 ---
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Re: Arabia still uses the Sundial for a practical use.

[Kevin Karney]

Brian (thanks for the warning) and for those who cannot use BBC iPlayer, I have 
uploaded a 4 minute clip from the broadcast. You can find it at

http://www.precisedirections.co.uk

Also, Julian Lush kindly responded to me
quote
 Much has been studied and written about Omani afalaj (the man-made water 
 courses which contour the hills), the araf or knowledgeable who controls 
 the distribution (of water) and the old time marking by sundials and, by 
 night, by the stars (it's a round-the-clock business). John Wilkinson did 
 various learned papers in the 1970-80s and Harriet Nash recently did a major 
 study on the use of stars (BAR S2237 ).
 
 I tried to find an extant sundial in Oman in 2010. What I found was pretty 
 defunct, but I remember a working one in Ibri in 1961-3, but it has long 
 since disappeared.
quote

If your computer cannot read a .m4v video file, please let me know.

Best wishes
Kevin

On 24 Feb 2013, at 19:05, brianalbinson brianalbin...@shaw.ca wrote:

 Kevin
 
 Unfortunately BBC  iPlayer  is only available in the UK.  I wonder if you 
 could post some still pdf's?
 
 Brian Albinson
 
 Vancouver, Canada
 
 
 
 
 On 2/24/2013 8:52 AM, Kevin Karney wrote:
 Dear Diallists
 
 BBC 2 have just started a nature series called Wild Arabia. In showing how 
 scarce water resources are shared out, they show an ancient Omani gentleman 
 using a sundial with an even more ancient wooden gnomon !
 
 The series is worth watching if you can get BBC2, but you can view this 
 episode on BBC iPlayer...
 
 http://www.bbc.co.uk/iplayer/episode/p013mrl8/Wild_Arabia_Sand_Wind_and_Stars/
 
 The context to the water storey is at minute 33:51; You see the sundial at 
 minute 36:00.
 
 Do watch and enjoy!
 
 Best wishes
 Kevin
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 https://lists.uni-koeln.de/mailman/listinfo/sundial
 
 
 
 
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Re: conservation

[Kevin Karney]

Frank
Just to confirm what Harriet has told you. The Church authorities, the National 
Trust and (for example) the Wye Valley AONB can only use certificated 
stonemasons. You could probably easily find the most suitable locally 
certificated person from the Clerk-of-Works for Durham or Newcastle cathedral.

As a second point, lime mortar adheres well but remains slightly plastic and 
sets very slowly, allowing proper settling of the stone around it. Once set, 
lime mortar gets stronger and stronger with time - until after a thousand years 
or so it has converted back - by reaction with atmospheric CO2 - to the Calcium 
Carbonate from which it was originally made. 

Best wishes
Kevin

On 28 Jan 2013, at 16:27, Frank Evans frankev...@zooplankton.co.uk wrote:

 Greetings fellow dialists,
 The topic of conservation is not much touched upon in the sundial list. I am 
 currently interested in the conservation of a sandstone church dial. Several 
 local church dials, some very old, have be conserved by experienced and 
 professional stonemasons but they have used cement for pointing and so on.
 
 Recently a stonemason told me that this was wrong and that for stonework lime 
 mortar should be used. Lime mortar has been in use since at least Roman times 
 and yet it is only now that I have been told that it is more suitable than 
 cement for stone repair. Can anyone say how long this information has been 
 about and how valid is it?
 
 A second lesser point: conservation of dials on English parish churches seems 
 to be undertaken by stonemasons who live many miles away while competent 
 local stonemasons are overlooked. Is there some kind of ecclesiastical list 
 of acceptable people who get the work?
 Frank
 55N 1.5W
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Re: Sundials worthy of a tour in England - Pics 1 for Bath

[Kevin Karney]

Dear SaraNice to hear from you!First idea...Bath - the Grand Pump Room built 1705 - an elegant tea room - with a fabulous Tompion Long Case Clock, complete with EoT cam, and on a ledge outside the nearest window the Tompion sundial with which to set the clock. The Curator has a packaged talk about the Pump Room, Tompion, the clock  the sundial - which he gives at breakfast time on the days the clocks change to/for summer time, when he open the clock and re-sets the clock. I am sure he could be pursued to talk to your group if you lunched there.2 more Pics to comeBest regardsKevin---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Hurray of Oz !

[Kevin Karney]

Peter
You start the engine, listen to it phutting away, read the engine plate to make 
sure you are in the right frame of mind, sit  beside it in the sun - dreaming. 
Then, by magic, just like any sundial, you notice the shadow of engine is 
really quite short. So it's noon and you go to lunch.
K

On 23 Jan 2013, at 16:54, Peter Tandy p.ta...@nhm.ac.uk wrote:

 A great stationary engine Kevin,….but how does it tell the time?...
  
 Peter Tandy
  
 From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Kevin Karney
 Sent: 23 January 2013 12:51
 To: Sundial list Sundial list
 Subject: Hurray of Oz !
  
 A rare engine from Australia circa 1930 2hp Sundial type B engine ….
 Best wishes 
 Kevin
 
 image001.jpeg

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Re: new app Sol Et Umbra for Android

[Kevin Karney]

Very jealous!Can someone translate the code to iPhone.
Please!
Kevin

Kevin Karney
Freedom Cottage, Llandogo, Monmouth, NP25 4TP
Phone 01594 539 595. Mobile 07595 024 960

On 9 Oct 2012, at 22:59, Simon [illustratingshadows 
illustratingshad...@yahoo.com wrote:

 very nice app, beat me to it! :)
  
 Simon
  
 Simon Wheaton-Smith
 www.illustratingshadows.com
 Phoenix, Arizona, W112.1 N33.5
 From: sun.di...@libero.it sun.di...@libero.it
 To: Sundial list Sundial list sundial@uni-koeln.de 
 Sent: Tuesday, October 9, 2012 1:49 PM
 Subject: new app Sol Et Umbra for Android
 
 If you own an Android device (smartphone or tablet) you may want to take 
 advantage of the new app Sol Et Umbra that means Sun and Shadow.
 It is available for free from the usual Google app market.
 
 Sol Et Umbra is basically an app that shows sun ephemeris for the actual (or 
 whichever desired) time and date:
 - latitude and longitude
 - right ascension and declination
 - local azimuth and height
 - equation of time
 - local or time zone sun time
 - local or time zone mean time
 - time of rise, set and transit (local noon)
 - total number of hours of light
 
 Moreover Sol Et Umbra shows the time using italic, babilonic and temporal 
 time 
 systems.
 It also shows the time of Muslims prayers (that are strictly related to the 
 position of the sun): Fajr, Zuhr, Asr1, Asr2, Maghrib and Isha.
 
 Sol Et Umbra can use the orientation sensors available in the device in order 
 to compute and show the time lines of a sundial designed on the plane of the 
 display. 
 The graph is updated after any movement of the device.
 
 Finally the app can show the lighting conditions of a dial that is drawn on 
 the device plane by means of an azimut / height graph that shows for any day 
 in 
 the year and for any hour in the day when the dial is lighted.
 
 More information on the program are available from my site: http://digilander.
 libero.it/orologi.solari/download/SolEtUmbraENU.html
 
 Ciao.
 Gian
 ---
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eBay : ANTIQUE HELIOCHRONOMETER BRONZE SUN DIAL SCIENTIFIC INSTRUMENT

[Kevin Karney]

I came across the attached on eBay

http://www.ebay.co.uk/itm/ws/eBayISAPI.dll?ViewItemitem=320976724417ssPageName=ADME:B:SS:GB:1123

anyone interested?

Kevin Karney

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Re: Sundial on Mars

[Kevin Karney]

Gnomon (γνώμων) is an ancient Greek word meaning indicator, one who 
discerns, or that which reveals. It has come to be used for a variety of 
purposes in mathematics and other fields.

Best regards
Kevin Karney


On 10 Aug 2012, at 16:21, rPauli wrote:

 We have to define gnomon  - as something perhaps common to all sundials.
 It is information reflected off the device.   Must a gnomon cast a shadow?
 
 
 On 8/10/2012 7:41 AM, brick...@62bricks.com wrote:
 Color calibration was the primary function, however these sundials - which
 are also on the previous Mars rovers - were in fact designed to also be
 used to show time and season. Originally they were meant to be placed on
 stationary landers. Since rovers can change direction and latitude, making
 permanent lines a problem, the solution was to superimpose time indicator
 lines on the images digitally so the dial can be read, as in this photo
 from the Spirit rover:
 
 http://www.nasaimages.org/luna/servlet/s/fb8nc5
 
 Here is an article (in PDF) from 2003 describing the design and operation
 of the Mars sundials:
 
 
 http://www.astro.washington.edu/users/woody/MarsDial.Plan_Rept.Jan04.pdf
 
 
 Don Rogerson
 
 
 David,
 
 On
 http://wtvr.com/2012/08/03/nasa-mars-rover-curiosity-will-land-early-monday/
 you can read that de 'sundial' is not used to have information  to
 calculate time of day, date, and seasons but as an appliance to color
 balance the photgraphies Curiosity made.
 
 
 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 10-aug-2012, om 11:03 heeft da...@davidbrownsundials.com het volgende
 geschreven:
 
 Dear Diallists,
 I thought you might find this particularly interesting, sent to me by my
 USA-based son.
 
 http://mars.jpl.nasa.gov/msl/multimedia/interactives/learncuriosity/index-2.html
 then click on the arrow until you get to the description of the 'Back'
 Click on the sundial (near the top/middle)
 
 Also:
 
 http://www.pcworld.com/article/260579/mars_rover_curiosity_a_complete_guide_to_tagging_along_online.html
 
 
 
 In particular:
 https://twitter.com/marscuriosity
 https://twitter.com/sarcasticrover  (unofficial I'm guessing :)
 
 David Brown
 Somerton, Somerset, UK
 
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Looking for Erich Pollähne

[Kevin Karney]

Can anyone help? I am trying to buy one of Erich Pollähne's perspex sundials. 
His company - Meku - has a website 

http://www.meku-pollaehne.de/Produkte/Sonnenuhren/sonnenuhren.htm

and price list, but no response to my e-mail. Does he still trade?

Thanks
Kevin Karney
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Re: Moore Sundial stolen

[Kevin Karney]

Luke
Great News !
thanks
Kevin
On 22 Jul 2012, at 17:41, Luke Coletti wrote:

 
 A bronze sculpture worth £500,000 stolen from the former home of British 
 artist and sculptor Henry Moore has been recovered by detectives after a 
 televised appeal for information.
 
 The Sundial, created by Moore in 1965 as a working model for a larger 
 sculpture, was found at an undisclosed location after an inquiry by 
 Hertfordshire Police led to the arrest of three men on suspicion of theft.
 ... 
 http://www.dailymail.co.uk/news/article-2177140/Stolen-bronze-Henry-Moore-sculpture-worth-500-000-recovered-following-TV-appeal.html
  

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Re: Calculating azimuth of sunrise and sunset from present back 25, 000 years

[Kevin Karney]

To get a small indication of the variation that occurs over long periods of 
time, you could try the excellent, easy to use and free Horizons program from 
JPL-NASA. It will take you back to 3000 BC. That's a step on the way to 25000 
years.

The program has a good web interface. Just google JPL Horizons to find it.

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth, NP25 4TP
Phone 01594 539 595. Mobile 07595 024 960

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Re: Why are schools, across the world, 'banning' analemmatic sundials ?

[Kevin Karney]

Martina
Gian is quite right. But one must try… So you need a strategy to overcome the 
stupidity. Why not recommend to your school the superb Mac Oglesby Beam  Spar 
dial (equiangular - so correctable for summer time and EoT!). This is designed 
for boy scouts/girl guides and involves ropes (children will hang themselves) 
and tree climbing (broken legs guaranteed) and - dare I say it - knives (child 
murder inevitable). So that is bound to be refused. Now you suggest a gentle 
analemmatic in its place and the authorities will melt with happiness at its 
simplicity and safety.

Or fight the dead hand of bureaucratic idiocy with its own kind. Do a full risk 
assessment of all potential  dangers and provide the strategy required to 
overcome each risk. (Sun hats against the sun …. non-poisonous paints … pre-cut 
lengths of string … old fashioned supervision of rowdy children … a tool-box 
talk etc etc).

My heart goes out to you and I hope you show copies of this e-mail thread to 
your head teacher and point out that there are very few things in the current 
overcrowd curriculum that can gently and cheaply draw together the diverse 
threads of art, history, astronomy, geography, geometry and maths as sundials 
in the playground. And they get the children out of the unhealthy atmosphere of 
the class room into the great outside.

Good luck  - you have my full support
Kevin Karney

On 15 May 2012, at 19:16, sun.di...@libero.it wrote:

 Against stupidity the gods themselves contend in vain. ~ Friedrich Schiller 
 
 Ciao.
 Gian
 
 Messaggio originale
 Da: martina.addisc...@gmail.com
 Data: 15/05/2012 19.23
 A: sundial@uni-koeln.de
 Ogg: Re: Why are schools, across the world,  #39;banning#39; analemmatic 
 sundials ?
 
 In message C999F252986D457EA20FAC7AD947B60D@samsung
 Reinhold Kriegler reinhold.krieg...@gmx.de wrote:
 
 
 Dear Martina,
 
 I still remember your previous message!
 
 
 The world is crazy!
 
 
 In Germany I have heard in a radio transmission last year, parents went
 to a lawyer after there children fell over a tree root while walking
 with the class on a public path through a forest… and private forest
 owners are thinking of no longer allowing people to walk on their paths
 through the forest… as they had to fight with several reports at the law
 courts!
 
 My beautiful analemmatic sundial was destroyed by jealouse women
 colleagues and they worried a lot about a friendly newspaper article. I
 was even called by the headmistress and she was not ashamed to tell me
 “There are also other good teachers at our school!” – because of a
 harmless sentence of a 10 years old girl about me! Nothing else! So you
 see where the real danger is! It is the jealousy, nothing else!
 
 http://www.ta-dip.de/sonnenuhren/meine-sonnenuhren/analemmatische-sonnen
 uhr.html 
 
 
 
 Dear Reinhold,
 
 Thanks for your reply, saying you also had some difficulty with
 an 'analemmatic' sundial at a school - and caused by jealousy
 plus people being frightened of some legal action, against them.
 
 As you suggest, I would love to 'defy' our Educational Authority
 to install this feature - but if I did so, then I am afraid that
 both myself and my Head Teacher will be dismissed from our jobs.
 
 
 I really cannot understand why (say) any Hop-scotch grids and
 Snakes  Ladders layouts are OK for playgrounds - but when it
 comes to interactive Human Sundials, they are deemed 'dangerous'
 for children.  Nobody seems to be able to give me a satisfactory
 explanation for it - except to say, Health and Safety reasons.
 
 
 If anyone else has some ideas on this, then please let me know.
 
 
 Sincerely,
 
 Martina Addiscott.
 
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Re: Question re Astro Compass mark II

[Kevin Karney]

John
I think the base is such that either an Astro Compass could be mounted - or a 
normal magnetic compass with the same fitting. The screws on the side of the 
mount are connected to two little magnets inside the base. These are used to 
compensate for the magnetism of the plane's fuselage. I would STRONGLY advise 
not to try to disassemble the base - I managed to damage mine - made of softish 
brass - while trying to get inside…. If the screws still work and move the 
internal magnets, you should be able to detect that with a common magnetic 
compass.
Trust that this helps

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595
On 27 Feb 2012, at 02:36, John Pickard wrote:

 Good morning,
  
 I have an Astro Compass mark II in excellent condition, made by Sperti 
 (Cincinnati) and when I bought it, it came with a base made by Dominion 
 Electric Protection Co of Canada. I also have a second base (bought from a 
 junk shop in Australia) engraved RAAF  G5A/366 and AWA 891. From this, I 
 assume that it was made by Amalgamated Wireless Australia (Sydney, Australia) 
 for the Royal Australian Air Force. But the two bases are quite different as 
 seen in the attached images.
  
 The Canadian base is hollow tube with a black crinkle finish while the RAAF  
 base is painted grey, but more significantly, it has a cylinder fitted in the 
 bottom, retained by brass screws countersunk into the tube of the base. Four 
 knurled brass knobs in the side of the base are arranged at 90o intervals, 
 with two higher, and two lower on the base. Removing these reveals holes with 
 square pegs. These pegs are obviously meant to take some sort of adjusting 
 key.
  
 While I could dismantle the cylinder from inside the base, I'm reluctant to 
 do this until I have a better idea of the function of the cylinder.
  
 The Sperti instructions make no reference to such a base, and all the other 
 instructions and illustrations I could find on the web show a hollow base:
  
 Instructions: http://myjunkshop.com/astro/astronew.html are an older version 
 of the same Sperti instructions that I have. Instructions by W.W. Boes  Co 
 (Dayton) (http://www.scribd.com/doc/3856694/AstroCompass-Manual BEWARE of 
 numerous pop-ups etc. that are impossible to kill) show a base without the 
 four knurled knobs in the side, i.e. it is the same as the Canadian base.
  
 Illustrations: http://www.prc68.com/I/AC_D500.shtml show the Sperti hollow 
 base, and those at 
 http://cadrans-solaires.pagesperso-orange.fr/navigation/astrocompass/astrocompass_uk.html
  show a similar hollow base.
  
 Does anyone have any idea of the function of the cylinder fitted into the 
 base made for the RAAF? If the Astro Compass were a magnetic compass, I would 
 imagine that the square pegs were for adjusting out magnetic influences when 
 fitted inside a vehicle or aircraft. Such adjustment screws are standard in 
 e.g. aircraft standby magnetic compasses, and are used when swinging the 
 compass. I did this myself when I had such a compass mounted in my Landrover 
 years ago (and it was surprisingly accurate). But such adjustment seems 
 counter-intuitive and unnecessary in an Astro Compass.
  
  
 Many thanks, John
  
 John Pickard
 john.pick...@bigpond.com 
 Canadian and AWA bases top view tiny image.JPGAWA base bottom view tiny 
 image.JPGCanadian and AWA bases side view tiny 
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Re: medieval astronomy (was: Georg of Peuerbach)

[Kevin Karney]

Sara wrote 
By the third century BC there were so many of them that people complain about 
having to run their lives by these blasted timepieces.

I guess this is her source

Titus Maccius Plautus 254 - 184 BC - a influential Roman playwright of comedies 
- is quoted, in 'Attic Nights' by Aulus Gellius ca 125 - after 180 BC, as 
saying…..

The Gods damn the man who first discovered the hours and - yes - set up a 
sundial here which has smashed the day into bits.When I was a boy, my stomach 
was the only sundial, by far the best and truest compared to these: it used to 
warn me when to eat.

I have the same complaint these days - but it is about iPhones, TV, computers

Best regards
Kevin

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Re: a reverse sundial for the blind

[Kevin Karney]

Hi Papa Ephraim

The method is theoretically fine - but only if:
 
a)  one corrects for DST, longitude AND for the equation of time, which 
varies the difference between local mean and local solar time by +/- quarter of 
an hour depending on the time of year

b)  one points the watch's hour hand at the sun itself with the plane of 
the watch in the plane of the ecliptic (i.e. the 6am to 6pm line on the watch 
is East/West - but you don't know where East and West is - so that's a real 
Catch-22. 

It is NO GOOD either to keep the watch horizontal and use the meridian from the 
sun to the horizon as one's sighting line or to face the sun and then raise up 
the watch face - BIG errors are introduced, especially when the sun is high in 
the sky.

c)  you can sight down from the angled watch face onto the horizon - 
virtually impossible in the tropics.

I doubt whether this is a practical method for a blind person

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595



On 11 Oct 2011, at 13:43, byzmusic wrote:

 I have written the following small article to help the blind navigate using 
 the position of the sun. But before it is published in a periodical for the 
 blind, I would like to know if anyone could tell me if all my statements are 
 scientifically correct.
 Thank you very much.
 Papa Ephraim
 
 Here's the article:
 
 Knowing which way is north can be very helpful when navigating in unfamiliar 
 places. An easy trick to determine your orientation is to point the hour hand 
 of your watch at the sun, and south will be halfway between it and 12:00 noon 
 on your watch (or halfway between it and 1:00 when on daylight savings time). 
 This method works even without a watch, as long as you know roughly what time 
 it is so that you can imagine where the hour hand of a watch would be. It is 
 a reverse sundial because instead of determining the time using the sun's 
 position and a dial aligned north, north is determined using the sun's 
 position and the time.
 
 In the Southern Hemisphere this method is inverted: Before pointing the hour 
 hand of your watch at the sun, you need to flip your watch upside-down, so 
 that the back side of your watch (which is usually touching your skin) is 
 facing you. Then north (not south) will be halfway between the hour hand and 
 12:00 on your watch.
 
 This method is accurate enough for most practical purposes except in 
 locations near the equator. One way to improve its accuracy is to adjust the 
 calculation based on your longitude. Instead of finding the halfway point 
 between 12:00 and the hour hand of the current time, subtract from the 
 current time eight minutes for every degree longitude west you are located 
 from the central meridian of your time zone. The central meridian in most 
 places around the world is a multiple of fifteen (because there are 
 twenty-four time zones in 360 degrees around the globe). For example, if you 
 are in Tucson, Arizona, the longitude is 111 degrees west. This is six 
 degrees west of the central meridian of Mountain Time Zone, which is located 
 at 105 degrees west (a multiple of fifteen). Six times eight is forty-eight, 
 so to determine south in Tucson it is necessary to imagine where the hour 
 hand would be after subtracting forty-eight minutes from the current time, 
 and then find the halfway poin!
 t between that imaginary hour hand and 12:00. If you are east of your time 
 zone's central meridian, you add (instead of subtract) eight minutes for 
 every degree longitude east of it you are located.
 
 A simple non-visual technique to find the sun's position precisely on a sunny 
 day is to rotate until you feel the sun on your face. Then cover your face 
 with your palm and gradually move it away from your face in the direction 
 necessary to keep its cool shadow on your face. Once your arm is fully 
 extended with your palm's shadow still on your face, you will know quite 
 accurately where the sun is.
 
 
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Re: Where it wil be equinox, at noon

[Kevin Karney]

Alex

You say in your note But in mathematics uuuf, - but this is not 
mathematics, it's astronomy! Nothing in the heavens moves with absolute 
uniformity…..

If you want the very best astronomical calculations, then you must use the best 
technology and that is provided free by NASA-JPL. Their software is used to put 
spacecraft on Mars etc. and is continuously updated for changes in Delta T. You 
can access their software - which is called Horizons - at
http://ssd.jpl.nasa.gov/horizons.cgi

The people who produce the Astronomical Almanacs use JPL's routines for the 
positions of solar system objects


Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595
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Re: longest day

[Kevin Karney]

It's worth remembering that all these things were well understood long ago. 
Ptolemy wrote a whole chapter about the changing length of the solar day in the 
Almagest nearly 2000 years ago…. 

On the inequality in the solar days
……it seems appropriate to add a brief discussion of the subject of the 
inequality of the solar day. A grasp of this topic is a necessary prerequisite, 
since the mean motions which we tabulate for each body are all arranged on the 
simple system of equal increments, as if all solar days were of equal length. 
However, it can be seen that this is not so. The revolution of the universe 
takes place uniformly about the poles of the equator. The more prominent ways 
of marking that revolution are by its return to the horizon, or to the 
meridian. Thus one revolution of the universe is, clearly, the return of a 
given point on the equator from some place on either the horizon or the 
meridian to the same place; and a solar day, simply defined, is the return of 
the sun from some point either on the horizon or on the meridian to the same 
point. On this definition, a mean solar day is the period comprising the 
passage of the 360 time-degrees of one revolution of the equator plus 
approximately 0;59 time-degrees, which is the amount of the mean motion of the 
sun during that period; and an anomalistic solar day is the period comprising 
the passage of the 360 time-degrees of one revolution of the equator plus that 
stretch of the equator which rises with, or crosses the meridian with, the 
anomalistic motion of the sun in that period. This additional stretch of the 
equator, beyond the 360 time-degrees, which crosses the horizon or meridian 
cannot be a constant, for two reasons: firstly, because of the sun’s apparent 
anomaly; and secondly, because equal sections of the ecliptic do not cross 
either the horizon or the meridian in equal times. Neither of these effects 
causes a perceptible difference between the mean and the anomalistic return for 
a single solar day, but the accumulated difference over a number of solar days 
is quite noticeable……” Almagest III 9, translated by G.J. Toomer 

What is given above, describes - if you read it carefully - the two components 
of the equation of time. (0:59 time degree above = 59/60 of a degree)

Kevin

On 14 Sep 2011, at 22:44, Tom Laidlaw wrote:

 This article has an extra 71 sec, but it does not say exactly which day. On 
 the other side it has a deffciency of 75 sec.
 
 Apparent solar time, sometimes called true solar time, is determined by the 
 daily apparent motion of the observed Sun. It is based on the interval 
 between two successive returns of the Sun to the local meridian. The length 
 of a solar day varies throughout the year, and the accumulated effect of 
 these variations (equation of time) produces seasonal deviations of up to 16 
 minutes. Why, you may ask: Earth’s orbit is elliptical and the Earth’s axial 
 tilt. Consequently, apparent solar days are shorter in  March (26–27) and 
 September (12–13) than they are in June (18–19) or December (20–21). In 2010, 
 the greatest Universal Time(UT1) interval between apparent midnights (at 
 Greenwich) is 86,471 seconds and the shortest interval is 86,325 seconds.
 
 Ref. http://www.universetoday.com/14700/how-long-is-a-day-on-earth/
 
 Tom
 
  
 
 From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On 
 Behalf Of Tom Laidlaw
 Sent: Wednesday, September 14, 2011 2:25 PM
 To: 'Marcelo'; 'Frank Evans'
 Cc: 'Sundial'
 Subject: RE: longest day
 
 According to a wi9kipedia article the longest Apparent Solar Day is Dec. 22 
 at 24 hrs. 29.9 sec.
 http://en.wikipedia.org/wiki/Solar_time#Apparent_solar_time
 Does it have a name? How about Longest Apparant Solar Day
  
 Tom Laidlaw
 
 From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On 
 Behalf Of Marcelo
 Sent: Wednesday, September 14, 2011 12:49 PM
 To: Frank Evans
 Cc: Sundial
 Subject: Re: longest day
 
 I used to think that the longest day was the summer solstice. Methinks that 
 you refer to some effect from the Equation of Time. And I don't know if there 
 is a name for it. 
 
 2011/9/14 Frank Evans frankev...@zooplankton.co.uk
 Greetings, fellow dialists,
 I tried to astonish my grandson by telling him that this was the longest day 
 of the year. (I think this is correct; today is 24 hours and 22 seconds 
 long.) He replied by asking if there was a name for this day. He said he 
 couldn't find anything on the interwebs.
 
 I am being outplayed by a grandson! Any help with a name, please?
 Frank 55N 1W
 ---
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Re: Flow of medieval glass

[Kevin Karney]

Just to give some additional background - that probably added to the urban myth 
about the 'flow' of glass.

Anyone who cuts glass with a dry diamond (which my wife - a picture framer - 
does on a daily basis) knows that - having made the scratch - the glass will 
break easily by flexing the glass along the scratch - provided that one does 
not wait around too long. The reason given for this - contrary to all the heavy 
scientific evidence already provided - is that the diamond makes a perfect 
V-shaped scratch. But in a relatively short time - and at a molecular level - 
the glass rapidly anneals/flows to round-off the crisp bottom of the V. This 
makes it much more likely that the glass will not crack along scratch. My wife 
scores the glass and immediately flexes it : it parts perfectly every time. A 
thing I cannot emulate myself…. 

To get around this problem, many less handy glass cutters prefer to use a wet 
diamond cutter. These cutters have a little reservoir of kerosene that wets the 
scratch made by the diamond which slows the degradation of the V, and allows 
more time to make the break. Wet diamond cutters are supposed to last longer 
than dry ones. But, in the picture framing business, one does not wish to have 
the extra stage of cleaning kerosene smears off the glass,  as well as the 
usual fluff/insect stains/finger prints.

(Interesting how this gnomonic list gets off topic - but long may it continue.)

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595

On 10 Aug 2011, at 01:18, John Pickard wrote:

 Good morning all,
  
 The (alleged) flow of glass in old windows is covered by Jearl Walker in his 
 excellent The flying circus of physics 2nd edition, ISBN 978-0-471-76273-7 
 on p. 105.
  
 Walker provides a number of references on his website 
 (http://www.flyingcircusofphysics.com/) (Click on link to Chap 2, and scroll 
 down to item 2.57 Flow of medieval cathedral window glass).
  
 Here are the references listed by Walker.
  
 2.57 Flow of medieval cathedral window glass
 This item is discussed in the book The Flying Circus of Physics, second 
 edition, by Jearl Walker, published
 by John Wiley  Sons, June 2006, 
 The material here is located at www.flyingcircusofphysics.com and will be 
 updated periodically.
 Comments
 References
 Dots  through  indicate level of difficulty
 Journal reference style: author, title, journal, volume, pages (date)
 Book reference style: author, title, publisher, date, pages
  Newton, R. G., “Fact or fiction? Can cold glass flow under its own weight 
 and what happens to stained
 glass windows?” Glass Technology, 37, No. 4, 143 (1996)
  Zanotto, E. D., “Do cathedral glasses flow?” American Journal of Physics, 
 66, No. 5, 392-395 (May
 1998)
  Zanotto, E. D., and P. K. Gupta, “Do cathedral glasses flow? --- 
 Additional remarks,” American Journal
 of Physics, 67, No. 3, 260-262 (March 1999)
  Stokes, Y. M., “Flowing windowpanes: fact or fiction?” Proceedings of the 
 Royal Society of London A,
 455, 2751-2756 (1999)
  Stokes, Y. M., “Flowing windowpanes: a comparison of Newtonian and 
 Maxwell fluid models,”
 Proceedings of the Royal Society of London A, 456, 1861-1864 (2000)
  
  
 While I can't offer any professional opinion on the evidence for flow or 
 urban myth, I have found Walker's book a great source of all sorts of arcane 
 information fully supported by documentation. It's also a great source of 
 information for high school physics etc. assignments! This is the sort of 
 book that shows how science is completely integrated into society. It's a 
 pity that such clear writing is not used in high schools to turn kids on to 
 science and physics. After all, how many of them know that planes are kept 
 in the air by Bernoulli's principle? And the same principle is responsible 
 for sand dunes etc. (I guess I'm preaching to the converted in this sundial 
 list!)
  
 Cheers, John
  
 John Pickard
 john.pick...@bigpond.com 
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Re: maximum attachment size on the sundial mailing list

[Kevin Karney]

Daniel
That's fabulous. 
I am sure many more images will be presented - which will just improve the 
already excellent service that you provide to us all. I am sure many others 
will join me in thanking you.

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595

On 8 Aug 2011, at 13:49, r...@infraroth.de wrote:

 Dear subscribers of the sundial mailing list,
 
 some time ago I asked the audience here about the maxiumum attachment size 
 accepted. From the responses I had received I derive that setting it up from 
 50 kB to 250 kB will not cause problems for the subscribers.
 
 If I do not get any complaints I will set the maximum size for attachments to 
 250 kB in the next days.
 
 Best regards -
 - Daniel Roth, sundial mailing list
 
 
 
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Re: Welsh SGS maker

[Kevin Karney]

Hi all
Capel Hanbury-Tenison is a neighbour and friend of mine. He makes very 
reasonably priced machine-engraved brass dials on commission - mostly 
horizontal and armilliary. But he will also turn his hand to make any kind of 
dial anyone might need - see the stained glass dial on his website 
www.bordersundials.co.uk. His e-mail address is copied above He is a member of 
the BSS and should become a member of this e-mail list (Capel - give me a call 
about this).

Although this e-mail is titled Welsh SGS maker - we both live in the county of 
Monmouthshire on the border between England and Wales.
Politically Monmouthshire is in Wales - but culturally it is in neither - 
generally considering itself independent having been a battle ground between 
the English  Welsh since pre-Roman days….

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595

On 8 Aug 2011, at 16:54, Larry Bohlayer wrote:

 In attempting to bookmark one of his web pages, the name Capel Tenison 
 appears as part of the default text offered for the bookmark title.
  
  
 Here is his LinkedIn page
 http://uk.linkedin.com/pub/capel-tenison/b/224/410
  
  
 Larry
  
 Larry Bohlayer
 Celestial Products
 608 Coral Bells Ct NW
 Concord, NC 28027-8034
 540-338-4040
 Fax 704-973-7799
 la...@celestialproducts.com
 www.celestialproducts.com
  
 From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On 
 Behalf Of John Carmichael
 Sent: Monday, August 08, 2011 10:57 AM
 To: sundial@uni-koeln.de
 Subject: Welsh SGS maker
  
 I came across this website showing a company in Abergavenny Wales UK that 
 makes SGS- “Border Sundials”  See: 
 http://www.bordersundials.co.uk/content/vertical_sundials.php
  
 Here you can see a stained glass sundial made by them.
  
 I could not find the name of the company owner.  Does anybody on the Sundial 
 list know who the owner is?  Perhaps he is a member of the BSS?
  
 Thx,
  
 John C.
  
  
  
  
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Re: Old sundial pictures

[Kevin Karney]

Sara
The pictures are now on
www.precisedirections.co.uk
Best regards
Kevin
p.s. Sara, I sent you an e-mail on 8th May re a visit to Boston/Cambridge - did 
it get spammed-out ?

On 30 Jun 2011, at 01:52, Schechner, Sara wrote:

 Did I miss part of this thread?  I am curious to see the images referred to.  
 Are they posted on a website?
 
 Sara
 
 42°21'N   71° 14'W 
 
 
 -Original Message-
 From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On 
 Behalf Of Donald Christensen
 Sent: Wednesday, June 29, 2011 6:24 PM
 To: Kevin Karney
 Cc: Sundials List
 Subject: Re: Old sundial pictures
 
 Kevin
 
 I really like the St Petersburg one! the other black and white g792092
 is another great one.
 
 Thank you.
 
 Does anyone have any older ones? A scanned image from a book will do.
 
 dchristensen...@gmail.com
 
 On 6/30/11, Kevin Karney kar...@me.com wrote:
 Hi Donald
 Any of these of any use?
 I personally love the Victorian lady picture (a memento mori - see what the
 gardner is carrying)
 and the one from St Petersburg palace with the communist apparatjik, showing
 the secret service man, the poor peasant and the school teacher how the dial
 works
 Where are you based ? I also lecture on the history of Sundials...
 
 
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Re: time, off topic

[Kevin Karney]

Fitzroy was the geek of his time - he was rich enough to own 22 chronometers 
and he was interested in everything - (especially meteorology - hence the 
Shipping weather forecast zone called after his name and the Fitzroy Storm 
Glass) A 'normal' naval ship in those days carried three chronometers - the 
average of the two which showed the closest time was used to  compute longitude

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595

On 23 Jun 2011, at 09:51, Frank Evans wrote:

 During Darwin's famous voyage aboard the Beagle, Captain Fitzroy had 22 
 chronometers aboard, no doubt to obtain accurate longitudes. This seems 
 pretty excessive and I'm wondering how many (or few) chronometers would have 
 reduced his time errors to an acceptable level. Any thoughts? Poisson 
 distribution, perhaps?
 Frank 55N 1W
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Re: EoT diagram

[Kevin Karney]

Chi Lian
It's good to see someone thinking about the EoT !

And to other contributors, many thanks for your additions concerning watches 
and clocks, which I was most interested to see

If you visit 
www.PreciseDirections.co.uk 
Click on the Sundials link and then click the last item on the list there 
Representing the EoT, you will find a number of curves representing EoT, 
including both the kidney polar curve and it's 'intrinsic' counterpart. The 
later - with equal spacing between points is marginally easier to read, but is 
no use for mechanical devices.

The problem with the kidney curve - mechanically sound though it is - is that 
it is just plain UGLY. Also it fails my test, which is does it teach anything 
about the sun, astronomy and sundials? The answer, I think, is Not much.

So I prefer mechanical representations of the EoT which generate the two 
components (obliquity and eccentricity) visibly and separately and then 
recombine them. (The second and fifth item on my sundials web page, mentioned 
above, are movies showing these in operation)

However, the master of all mechanical EoT generators must be the device in the 
Strassburg cathedral clock. I cannot find a web picture of this, but I have 
posted a not-very-clear photo of it at the above web-site

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595


On 21 Jun 2011, at 17:11, Chiu 邱,Chi lian wrote:

 Hi,
 
 I figured out a way to plot EoT curve which I didn't see in sundial books I 
 own. 
 Diagram is enclosed here.
 
 For a better resolution one, see
 http://dl.dropbox.com/u/31382133/EoT%20.png
 
 Best regards,
 
 ChiLian   24.8N 121E
 EoT_S .png---
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Re: varying speed?

[Kevin Karney]

Brent
If you measure the transit of a star (or any celestial body) through the 
meridian again and again over many years with telescopes that can distinguish 
less than 1 second of arc, then it's perfectly possible. Remember 1 second of 
time = 15 seconds of arc. These measurements - now done automatically -  have 
been done for years by using transit telescopes to take photographs of the 
stars and then by taking measurements off the photo plates.

Even without sophisticated instruments, surprising accuracies were obtained...

 Malik Shah the grandson of Toghril Beg, the founder of the Seljuk dynasty 
 ruled the city of Isfahan from 1073 AD. His vizier Nizam-ul-Mulk invited Omar 
 Khayyam to Isfahan, to set up an observatory. Other leading astronomers were 
 also invited to work at the observatory and for 18 years Omar Khayyam led the 
 scientists and produced work of outstanding quality. It was a period of peace 
 during which the political situation allowed Khayyam the opportunity to 
 devote himself entirely to his scholarly work. During this time Khayyam led 
 work on compiling astronomical tables and he also contributed to calendar 
 reform in 1079. Khayyam measured the length of the year as 365.24219858156 
 days, we know now that the length of the year is changing in the sixth 
 decimal place over a person's lifetime. It is also outstandingly accurate. 
 For comparison the length of the year at the end of the 19th century was 
 365.242196 days, while today it is 365.242190 days. 

Omar Khayyam was a real polymath - a notable astronomer, mathematical and poet. 
He famously wrote 

 A Book of Verses underneath the Bough,
 A Jug of Wine, a Loaf of 
 Beside me singing in the Wilderness --
 Oh, Wilderness were Paradise enow!

and (especially for us gnomonists)

 For in and out, above, about, below,
 ’Tis nothing but a magic shadow-show,
 Play’d in a box whose candle is the Sun,
 Round which we phantom Figures come and go

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595

On 26 Mar 2011, at 13:57, Brent wrote:

 It's amazing that someone was able to calculate these
 numbers out to 6 decimals. Is that done by some type of
 observation or is it mathematics?
 
 How could you possibly measure something like that?
 
 
 
 On 3/25/2011 1:14 PM, Kevin Karney wrote:
 Nothing is constant in the heavens !
 The 'tropical' year (from equinox to equinox) is 365.242190 days
 The 'sidereal' year (fixed star to fixed star) is 365.256363 days
 The 'anomalistic' year (perihelion to perihelion) is 365.259636 days - 
 cycling over a period of some 21000 years
 (values for 2009 from Astronomical Almanac)
 But these are mean values having averaged out the effects of nutation (the 
 wobbling of the Earth's axis) and various other effects.
 
 ---
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Re: varying speed?

[Kevin Karney]

Marcelo 

Nothing is constant in the heavens !
The 'tropical' year (from equinox to equinox) is 365.242190 days
The 'sidereal' year (fixed star to fixed star) is 365.256363 days
The 'anomalistic' year (perihelion to perihelion) is 365.259636 days - cycling 
over a period of some 21000 years
(values for 2009 from Astronomical Almanac)
But these are mean values having averaged out the effects of nutation (the 
wobbling of the Earth's axis) and various other effects.

Perihelion is even more complicated
in 2010 - 3rd January 0 hrs
in 2011 - 3rd January 19 hrs
in 2012 - 5th January 1 hrs
in 2013 - 2nd January 5 hrs
in 2014 - 4th January 12 hrs
(values from US Naval Observatory web site)

This is strange behaviour - not just a leap year effect!  I have heard that 
this is because - from the Keplerean point-of-view - the Earth and Moon rotate 
as a unit in an ellipse around the sun - like an out of balance dumbell - whose 
centre of gravity is somewhere in the Earth's core but not at its centre. So 
the actual moment when the Earth is closest to the Sun depends on the position 
of the Moon. This was explained to me some 50 years ago by my uncle who was a 
dedicated but amateur astronomer. I have never it confirmed by a professional 
astronomer.

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595


On 25 Mar 2011, at 16:14, Marcelo wrote:

 Your question brought to my mind an old doubt.
 
 As the points of perihelion and aphelion are continually changing (in a very 
 slowly way, but they are), so the EoT is also changing from an year to 
 another, right? I mean, if a century ago perihelion and aphelion occurred not 
 in january and july, but in december and june (it's only an example, I don't 
 know how much time does it need to change), then the EoT was different. 
 
 2011/3/25 Marcelo mmanil...@gmail.com
 Hello Brent,
 
 as long as I know, the Earth's speed really has a variation throughout the 
 year, for its orbit being ellliptical, with the Sun in one of the ellipse 
 focuses, it is faster when nearer to the sun (perihelion) and slower when its 
 at maximum distance from it (aphelion). 
 
 Both the perihelion and aphelion are upon the ellipse's major axis.
 
 As a result, the sun's apparent ecliptical longitude changes a little slower 
 in july than it does in january.
 
 Further, as Earth's axis has a declination of ~ 23.5 degrees, that means that 
 the Sun's apparent longitude measured upon the Equator is slightly different 
 of its ecliptical longitude (measured upon the Earth's orbit plan).
 
 So, neither is the Sun moving from West to East regulary throughout the year, 
 neither is its movement on the ecliptic equal to that on the Equator - if Sun 
 moves 1 degree with relation to the ecliptic, it may move 58 minutes of arc 
 with relation to the celestial equator.
 
 
 2011/3/24 Brent bren...@verizon.net
 Hello again;
 
 I read this at:
 http://www.sundialsoc.org.uk/HDSW.htm
 
 Part 17
 When we look at the Sun we are observing it from a moving
 platform. It is the varying speed around its elliptical
 orbit and the tilted axis which are responsible for the
 daily variations accounted for by the Equation of Time.
 
 I'm confused about the varying speed part.
 Does the earth actually change speed as it travels around
 the sun or is it just the way we perceive it?
 
 thanks again;
 brent
 
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Re: A 14th century sundial question from France.

[Kevin Karney]

Dear Friends
Don't forget the beautiful Missal of St Leofric 10-11th Century for an elegant 
but simple shadow length table
see 
http://image.ox.ac.uk/show?collection=bodleianmanuscript=msbodl579
and find folio 58 recto

Does anyone know if Bede's Table is available in manuscript image form anywhere 
on the web (plus a translation...!)?

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595


On 9 Mar 2011, at 15:03, Schechner, Sara wrote:

 I had exactly the same thought as John—that this was a table of shadow 
 lengths in the form that Bede gives in the 7th century.
 Sara
  
  
 Sara J. Schechner, Ph.D.
 David P. Wheatland Curator of the Collection of Historical Scientific 
 Instruments
 Department of the History of Science, Harvard University
 Science Center 251c, 1 Oxford Street, Cambridge, MA 02138
 Tel: 617-496-9542   |   Fax: 617-496-5932   |   sche...@fas.harvard.edu
 http://www.fas.harvard.edu/~hsdept/chsi.html
  
  
  
 From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On 
 Behalf Of JOHN DAVIS
 Sent: Wednesday, March 09, 2011 5:13 AM
 To: Sundial Mailing List; Bill Gottesman
 Subject: Re: A 14th century sundial question from France.
  
 Hi Bill (and other dialling colleagues),
  
 The data that you show looks very similar to the Venerable Bede's shadow 
 length tables (though the values are slightly different). This gives the 
 length of a person's shadow on the assumption that their height is equal to 
 six of their own feet (tall people generally have big feet!). But the hours 
 are probably not the modern equal ones.
  
 This topic will be discussed in some detail in the forthcoming June issue of 
 the BSS Bulletin. A reason for the inaccuracies will be proposed, together 
 with a rather more accurate version of the same table, to be found in an 
 Anglo-Saxon manuscript.
  
 Regards,
  
 John
 -
 
 Dr J Davis
 Flowton Dials
 
 --- On Wed, 9/3/11, Bill Gottesman billgottes...@comcast.net wrote:
 
 From: Bill Gottesman billgottes...@comcast.net
 Subject: A 14th century sundial question from France.
 To: Sundial Mailing List sund...@rrz.uni-koeln.de
 Date: Wednesday, 9 March, 2011, 1:06
 
 Richard Kremer, the Dartmouth physics professor who brought the ~1773 
 Dartmouth Sundial to display at the NASS convention this past summer, asked 
 me the following question.  I have done a bit of modelling on it, and have 
 not been able to supply a satisfactory answer.  Is anyone interested in 
 offering any insight?  My hunch is that the astronomer who wrote this guessed 
 at many of these numbers, and that they will be estimates at best for 
 whatever model they are based on.  I have tried to fit them to antique, 
 equal, and Babylonian hours, without success.  In 1320, the equinoxes occured 
 around March and Sept 14 by the Julian Calendar, as best I can tell, and that 
 doesn't seem to help any.
 
 -Bill
 ---
 I've got a sundial geometry question for you and presume that either you, or 
 someone you know, can sort it out for me.
 
 A colleague has found a table of shadow lengths in a medieval astronomical 
 table (about 1320 in Paris).  The table gives six sets of lengths, for 
 2-month intervals, and clearly refers to some kind of gnomon that is casting 
 the shadows.  The manuscript containing this table of shadow lengths appears 
 in a manuscript written by Paris around 1320 by John of Murs, a leading 
 Parisian astronomer.  I don't know whether Murs himself composed the table or 
 whether he found it in some other source.  The question is, what kind of dial 
 is this.  A simple vertical gnomon on a horizontal dial does not fit the 
 data, which I give below.
 
 Dec-Jan
 hour 1 27 feet
 hour 2 17 feet
 hour 3 13 feet
 hour 4 10 feet
 hour 5 8 feet
 hour 6 [i.e., noon] 7 feet
 
 Nov-Feb
 1 26
 2 16
 3 12
 4 9
 5 7
 6 6
 
 Oct-Mar
 1 25
 2 15
 3 11
 4 8
 5 6
 6 5
 
 Sept-Apr
 1 24
 2 14
 3 10
 4 7
 5 5
 6 4
 
 Aug-May
 1 23
 2 13
 3 9
 4 6
 5 4
 6 3
 
 Jul-Jun
 1 22
 2 12
 3 8
 4 5
 5 3
 6 2
 
 Note that in each set, the shadow lengths decrease in identical intervals 
 (-10, -4, -3, -2, -1).  This might suggest that the table is generated by 
 some rule of thumb and not by exact geometrical calculation, for by first 
 principles I would not expect these same decreasing intervals to be found in 
 all six sets!
 
 I started playing with the noon shadow lengths at the solstices, looking for 
 a gnomon arrangement that yields equal lengths of the gnomon for shadow 
 lengths of 7 (Dec) and 2 (Jun) units.  If you assume the dial is horizontal 
 and you tilt the gnomon toward the north by 55 degs, my math shows that you 
 get a gnomon length of 2.16 units.  I assume that Paris latitude is 49 degs 
 and the obliquity of the ecliptic is 23.5 degs (commonly used in middle ages).
 
 I'm too lazy to figure out the shadow lengths

Re: Google's Art Project and dialling

[Kevin Karney]

Babylonian Hours - counted from Sunrise ?
The shadows in picture are not good - so don't assume the times will be right

The dial is not a polyhedral dial that one would set up in the garden which 
would read the same time on each face according to the time of day. Its a 
portable dial to be carried around (as a sign of one's sophistication?). My 
first guess was that one was supposed to get it pointing north with the compass 
and read standard hours. Turn it though 90 degrees about the polar axis and 
read Babylonian hours.
 
What is odd is that the dial is set for a latitude of 23.5 ° (a significant 
angle !) - nowhere near the latitude of London where the dial (and its 
predecessor in Holbein's portrait of Nicholaus Kratzer) were made.

Then, thanks to John Davies for making that connection, I took a look Peter 
Drinkwater's 1993 The Sundials of Nicholaus Kratzer. I quote... the 
conception of these Dials is brilliant, but its execution unperceptive and 
horologically useless  and  Holbein was a good observer and a 
meticulous recorder ... and ... what is depicted can do nothing: it is simply 
not right, and would seem to be a Kratzerian cock-up of magnificent 
proportions.

Does anyone know any of Peter Drinkwater's descendants? It would be nice to get 
their permission to re-publish his little booklet to the Sundial Mailing list.

On 5 Feb 2011, at 10:32, Alexei Pace wrote:

 If I may ask - why is the dial face (the one facing the viewer) on the 
 polyhedral dial different from the rest with the gnomon set on the 6 hour 
 line? Yet the time is just 1 hour behind the two times shown on the other two 
 dials.
 
 Regards
 
 Alex
 
 
 
 On Fri, Feb 4, 2011 at 8:59 AM, patrick_pow...@compuserve.com wrote:
 
 After only recently learning of the Google Art Project, I looked at Holbein's 
 Ambassadors today and like many others I was amazed at the resolution. This 
 huge painting, it's not far off 7ft square, is here in London at the National 
 Gallery and it is now available to view under Google's Art Project at:
 
 http://www.googleartproject.com/museums/nationalgallery/the-ambassadors
 
 Painted in 1533 it has the most interesting collection of contemporary 
 dialling equipment all of which are painted in immense detail.  There are two 
 globes (one terrestrial and one celestial), a quadrant, a torquetum, a 
 polyhedral dial and a shepherd's dial and some others I don't know, all of 
 which are set in such a way as to tell some 'story' to the understanding 
 viewer.
 
 Until now it has been almost impossible for a sundial-interested visitor to 
 the gallery to attempt to understand much of the detail - there just isn't 
 time - but now with this view you can. You can even see for yourself the four 
 place names marked on the terrestrial globe (one of which helped to identify 
 one of the depicted persons as Jean de Dinteville, the Seigneur of Polisy) 
 and you can even read the music and words in the open book and guess at the 
 date and time shown on the shepherd's dial..
 
 It doesn't (I think) help with viewing the anamorphic skull as a skull - or 
 at least you still have to turn your monitor round to do so! - and I STILL 
 don't understand the object behind the shepherd's dial...  Anybody know what 
 that might be?
 
 Patrick
 
 
 
 ---
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Re: Google's Art Project and dialling

[Kevin Karney]

Now take a look at Holbein's Nicholas Kratzer, painted in 1528 which is in the 
Louvre (copy in National Portrait Gallery). Kratzer was a German mathematician, 
astronomer and instrument maker who worked as King Henry VIII's astrologer. He 
was a drinking friend of Holbein. Find his picture in the Wikepedia entry for 
Nicholas Kratzer.

Holbein was probably using Kratzer's instruments in the Ambassador's picture, 
which was painted a few years later in 1533. Same shepherd's dial, same strange 
instrument, same polyhedral dial (but unfinished), same little dial-like thing 
with the spike and square hole on his table.

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595

On 4 Feb 2011, at 07:59, patrick_pow...@compuserve.com wrote:

 
 After only recently learning of the Google Art Project, I looked at Holbein's 
 Ambassadors today and like many others I was amazed at the resolution. This 
 huge painting, it's not far off 7ft square, is here in London at the National 
 Gallery and it is now available to view under Google's Art Project at:
 
 http://www.googleartproject.com/museums/nationalgallery/the-ambassadors
 
 Painted in 1533 it has the most interesting collection of contemporary 
 dialling equipment all of which are painted in immense detail.  There are two 
 globes (one terrestrial and one celestial), a quadrant, a torquetum, a 
 polyhedral dial and a shepherd's dial and some others I don't know, all of 
 which are set in such a way as to tell some 'story' to the understanding 
 viewer.
 
 Until now it has been almost impossible for a sundial-interested visitor to 
 the gallery to attempt to understand much of the detail - there just isn't 
 time - but now with this view you can. You can even see for yourself the four 
 place names marked on the terrestrial globe (one of which helped to identify 
 one of the depicted persons as Jean de Dinteville, the Seigneur of Polisy) 
 and you can even read the music and words in the open book and guess at the 
 date and time shown on the shepherd's dial..
 
 It doesn't (I think) help with viewing the anamorphic skull as a skull - or 
 at least you still have to turn your monitor round to do so! - and I STILL 
 don't understand the object behind the shepherd's dial...  Anybody know what 
 that might be?
 
 Patrick
 
 
 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial
 

---
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Re: Solar Position Calculator

[Kevin Karney]

Hi Kaarigar
Firstly WELL done. Your web interface is very nice. I think it's great when 
people get back to basics and understand the background physics/astronomy 
behind their gnomonics. I remember the satisfaction that came when I first 
worked things out and found I could generate results of surprising accuracy.

To calibrate your routines you should use NASA's JPL's Horizons program or US 
Naval Observatory MICA - which others have mentioned. The Horizons web 
application is superb inasmuch as it is easy-to-use, free, fast and can deliver 
results in spreadsheet format back to your computer. It is continuously updated 
for the earth's erratic slowing and its internal DE405 routines for the 
positions of solar system bodies are used by MICA as well - so represents the 
best available technology. The Horizons printable user guide (which you do not 
need) contains the wonderful exhortation if your career or spacecraft depends 
on a non-lunar satellite or small body ephemeris, contact JPL before using 
it

The most sophisticated do-it-yourself astronomical routines available are to be 
found in Meeus' book Astronomical Algorithms which is (I think) out of print, 
expensive but usually available on abebooks.com. (Does anyone know of a book 
that betters Meeus ???)

What is of interest to gnomonists are simple routines that give sufficient 
accuracy for sundials. I made a tiny check on your results for today at 8  20 
hrs UTC = midnight  midday California time using MICA.
RA was correct to 11 secs of arc
Declination was correct to 3 secs of arc
Altitude was correct to 21  87 secs of arc
Azimuth was correct to 82  39 secs of arc
The variable error in altitude  azimuth may be because you just calculated a 
geocentric RA  Decl, whereas to be entirely thorough one should calculate the 
topographic RA  Decl. But, on that tiny sample, your routines are MORE than 
good enough for any gnomonic studies !

A few small points to clarify on your web interface...
1) Right Ascension has no units, you have put it in degrees - but it is 
frequently quoted in hours ? Also, by convention, it is always rectified to 
within 0 - 24 hours or 0 - 360 degrees. (In contrast, Hour angles by convention 
are always rectified to -180 to +180 degrees).
2) Are your times in local mean time, local standard time or UTC? Your results 
seem to be in local standard time - which is logical !
3) The sign used for your longitude conforms to IAU convention, but many 
gnomonists seem to prefer +ve West

I was interested to know where you came from - so assumed your web interface 
default location was your home. You appear to live at sea, in the San Francisco 
Bay!!

What is the background of your calculations ?

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
51° 44' N 2° 41' W Zone 0
+ 44 1594 530 595


On 2 Feb 2011, at 20:22, triplederby100-pro...@yahoo.com wrote:




 



 I had asked a question earlier about how to design a contraption such that a 
 sunlight beam falls on a place (or point) exactly each year at a specific 
 time. Having gone through the responses and realizing that I will have to 
 learn to do some basic solar position calculations myself, I have implemented 
 it and made it available through a web site - please check it out and let me 
 know if it is right/wrong/ or simply works. Thanks!
 
 http://www.heliometry.com/solpos
 
 Kaarigar
 
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The Equation of Time - a simple movie to show its effect

[Kevin Karney]

Dear Friends
I have just put up onto my website
www.precisedirections.co.uk
a little movie made with Google Sketchup (which has quite reasonable algorithms 
for the Sun's position).
It show a horizontal dial at 1.30 pm every day of the year in a wonderful place 
where the sun shines every day in the afternoon.

If you have a copy of Sketchup (which is freely available from Google), I have 
also included the file from which the movie was made. It takes a little time to 
become familiar with Sketchup, but - for seeing how your dial will perform in 
the real world with nearby trees, surrounding buildings, etc. - there is 
nothing better...

Enjoy

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales UK
01594 530 595



 



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Re: Puzzle Photograph of the Eclipse - A complete guess

[Kevin Karney]

Dear Friends

With all this talk of pinhole photography, I thought you might like the 
attached - taken over a continuous 6 month period by Justin Quinell of Bristol 
over the famous Brunel suspension bridge. He uses a beer can with a nail hole 
as his camera The photos are made on photo paper placed in the can. The 
image (after six months) is produced just by scanning the undeveloped paper! 

You can see all his various amazing solar pictures in proper size and how he 
makes them at ...
http://www.pinholephotography.org/gallery/slow/index.html

Enjoy
Best regards
Kevin

Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP
01594 530 595
 
inline: Brunel Bridge Pinhole.jpg



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Re: Determing Pitcairn Island longitude in 233 B.C.

[Kevin Karney]

Interesting. The Chinese found the longitude of Mombasa in the 16 century (I 
think it was) without chronometers using eclipses, using the method outlined in 
the article.  With good means to predict the occurrence of eclipses, they 
planned such observations. 

Best regards and happy new year
Kevin

On 29 Dec 2010, at 04:56, R Wall wrote:

 Hi all,
 
 Found the following on the eclipse of the Moon on Pitcairn Island in 233 B.C. 
 They say that they were able to determine the longitude of Pitcairn Island 
 from the eclipse of the Moon and this was in 233 B.C.
 
 http://www.21stcenturysciencetech.com/articles/Pitcairn_Island.pdf
 
 Roderick Wall.
 
 
 
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Re: Special Seasonal Dates

[Kevin Karney]

Here's a graph of earliest sunset/latest sunrises for various latitudes...
It is calculated by using the 12 +/- [acos{tan(latitude) .  
tan(declination)}]/15 formula corrected to mean tim with the EoT
Best regards
Kevin
inline: Eariest:Latest.jpg
On 20 Dec 2010, at 14:26, Kevin Karney wrote:

 Dick
 Thanks for that correction. I am sorry I was being so insular and did not 
 think it all through.
 
 One is seeing the interplay between two equations : 
 1)sunset/rise being (more or less) = 12 +/- [acos{tan(latitude) .  
 tan(declination)}]/15 with declination change rather minimal around the 
 solstice
 2)equation of time changing rapidly around the winter solstice.
 
 There is a third influence - but I think it probably plays an insignificant 
 part - the difference between the usually quoted geocentric equation of time 
 and its topocentric cousin - which varies the equation of time by up to a 
 second dependent on both time of day and latitude.
 
 Best regards
 Kevin
 
 On 20 Dec 2010, at 12:39, kool...@dickkoolish.com wrote:
 
 The date of earliest sunset depends on Latitude and is not
 always Dec 14.  See: http://www.idialstars.com/eass.htm
 
 
 
 
 Dear Colleagues
 
 In the depths of a freezing Northern winter, there's time to think about
 days of special interest. There are six significant solar dates around
 this time of the year.
 
 Three are special and probably known to all...
 21st December  - half an hour before midnight - the Winter Soltice
 25th December - not only Christmas day, but one of the four days in the
 year when the equation-of-time is zero.
 3rd January - Perihelion when the Earth is closest to the Sun,
 
 One day is perhaps of interest only to the serious heliochronometer
 user...
 23rd December - the day when the equation of time is changing at its
 maximum rate of almost 30 secs/day
 
 Two days are nothing more than obscure, except to the numerically obsessed
 - or to those who like strange questions to ask on quiz nights
 14th December - the day on which the Sun sets earliest in the day
 29th December - the day on which the Sun rises latest in the day
 See the graph below. If you wonder why this is so, it is because there are
 two effects in play (a) the daily change in sunrise/sunset as a result of
 declination change is minimal around the solstice and (b) the effect of
 the equation of time with its large eccentricity component as the Sun
 races forward towards perihelion.
 
 p.s. the graphs are for 54 degrees North latitude; the y-axis scale will
 change at other latitudes.
 p.p.s. dates are UT - so they may vary with your local longitude.
 
 Have a wonderful Christmas season.
 
 Kevin Karney
 
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Re: Special Seasonal Dates

[Kevin Karney]

Dick
Thanks for that correction. I am sorry I was being so insular and did not think 
it all through.

One is seeing the interplay between two equations : 
1)  sunset/rise being (more or less) = 12 +/- [acos{tan(latitude) .  
tan(declination)}]/15 with declination change rather minimal around the solstice
2)  equation of time changing rapidly around the winter solstice.

There is a third influence - but I think it probably plays an insignificant 
part - the difference between the usually quoted geocentric equation of time 
and its topocentric cousin - which varies the equation of time by up to a 
second dependent on both time of day and latitude.

Best regards
Kevin

On 20 Dec 2010, at 12:39, kool...@dickkoolish.com wrote:

 The date of earliest sunset depends on Latitude and is not
 always Dec 14.  See: http://www.idialstars.com/eass.htm
 
 
 
 
 Dear Colleagues
 
 In the depths of a freezing Northern winter, there's time to think about
 days of special interest. There are six significant solar dates around
 this time of the year.
 
 Three are special and probably known to all...
  21st December  - half an hour before midnight - the Winter Soltice
  25th December - not only Christmas day, but one of the four days in the
 year when the equation-of-time is zero.
  3rd January - Perihelion when the Earth is closest to the Sun,
 
 One day is perhaps of interest only to the serious heliochronometer
 user...
  23rd December - the day when the equation of time is changing at its
 maximum rate of almost 30 secs/day
 
 Two days are nothing more than obscure, except to the numerically obsessed
 - or to those who like strange questions to ask on quiz nights
  14th December - the day on which the Sun sets earliest in the day
  29th December - the day on which the Sun rises latest in the day
 See the graph below. If you wonder why this is so, it is because there are
 two effects in play (a) the daily change in sunrise/sunset as a result of
 declination change is minimal around the solstice and (b) the effect of
 the equation of time with its large eccentricity component as the Sun
 races forward towards perihelion.
 
 p.s. the graphs are for 54 degrees North latitude; the y-axis scale will
 change at other latitudes.
 p.p.s. dates are UT - so they may vary with your local longitude.
 
 Have a wonderful Christmas season.
 
 Kevin Karney
 
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Re: Wonderful NREL Sun Position Calculator, in time for Solstice fun

[Kevin Karney]

If you want to do a bunch of calculations and work on them with e.g Excel, I 
recommend NASA JPL's Horizon's Program. http://ssd.jpl.nasa.gov/horizons.cgi. 
It is free, has a nice web interface and computes just about anything 
astronomical that you might want (although you have to deduce the EoT from the 
Apparent Solar Time). Results are downloadable directly to your computer either 
as text or .csv files. It is of course JPL who maintain the basic DE405 
routines that are used by just about all other professional programs.

The other great program is US Naval Observatory's MICA program available on 
disk for a few dollars. MICA uses DE405 as its ultimate engine.

Anyone who wants to use Meeus's routines, I have the whole lot as a callable 
Excel macro function

Best regards
Kevin Karney

On 20 Dec 2010, at 16:38, Bill Gottesman wrote:

 Hello Sundial-listers,
 
 I used to rely on Luke Coletti's Great Circle website's GROK calculator for a 
 precise calculation of sun positions, but that page has been non-operative 
 for about a year now.
 
 The National Renewable Energy Laboratory (NREL) in Golden Colorado has 
 provided an excellent resource at http://www.nrel.gov/midc/solpos/spa.html, 
 similar to GROK.  Their MIDC Sun Position Algorithm utilizes Jean Meeus' 
 modified VSOP87 algorithm, reportedly accurate to 0.0003 degrees between 
 years -2000 to +6000.   The NREL site also provides a link to an explanation 
 of this algorithm as a pdf file http://www.nrel.gov/docs/fy08osti/34302.pdf.
 
 The program will output a table of sun positions over a range of dates, in as 
 little as 1 second intervals.  It allows many options for sun position 
 measurements, but the most helpful to me are topocentric azimuth, geocentric 
 sun declination, Topocentric (uncorrected) sun elevation, and topocentric sun 
 elevation corrected for atmospheric refraction.  These tables are essential 
 to me in the field when I delineate true north using a theodolite, and lay 
 out predictive sightings for sunrise and sunset.
 
 Beware; if you select Topocentric Zenith Angle, the results are corrected 
 for refraction, though they do not tell you this up front.  You must select 
 Topocentric (uncorrected) sun elevation if you want to exclude atmospheric 
 refraction.
 
 Lastly, they report the time of sunrise/sunset as when the center of the sun 
 is 0.8333 degrees below the horizon (uncorrected for refraction).  This is to 
 account for the width of the sun, and an average effect of refraction, and 
 represents the moment that the advancing or receding limb of the sun (not the 
 sun's center) crests the horizon.
 
 -Bill
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Special Seasonal Dates

[Kevin Karney]

Dear Colleagues

In the depths of a freezing Northern winter, there's time to think about days 
of special interest. There are six significant solar dates around this time of 
the year.

Three are special and probably known to all...
21st December  - half an hour before midnight - the Winter Soltice
25th December - not only Christmas day, but one of the four days in the 
year when the equation-of-time is zero.
3rd January - Perihelion when the Earth is closest to the Sun,

One day is perhaps of interest only to the serious heliochronometer user...
23rd December - the day when the equation of time is changing at its 
maximum rate of almost 30 secs/day

Two days are nothing more than obscure, except to the numerically obsessed - or 
to those who like strange questions to ask on quiz nights
14th December - the day on which the Sun sets earliest in the day
29th December - the day on which the Sun rises latest in the day
See the graph below. If you wonder why this is so, it is because there are two 
effects in play (a) the daily change in sunrise/sunset as a result of 
declination change is minimal around the solstice and (b) the effect of the 
equation of time with its large eccentricity component as the Sun races forward 
towards perihelion.

p.s. the graphs are for 54 degrees North latitude; the y-axis scale will change 
at other latitudes.
p.p.s. dates are UT - so they may vary with your local longitude.

Have a wonderful Christmas season.

Kevin Karney



Sunrise-Sunset.pdf
Description: Adobe PDF document
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Re: Merry Christmas in all the languages

[Kevin Karney]

Steve
You express my sentiments entirely
Happy and joyous Christmas to all
Kevin

Kevin Karney
Freedom Cottage, Llandogo, Monmouth, NP25 4TP, Wales, U.K
Phone 01594 539 595. Mobile 07595 024 960

On 12 Dec 2010, at 05:08, Steve wrote:

 Confrere:
 
  Like most, sometimes I just sit and other times I sit and think.  
 Perhaps with the holidays approaching and the turmoil in the world, I was 
 thinking that the whole world should have a list like ours.  You look at the 
 names, people from all over the world and both genders.  You read the emails, 
 different ideas, different methods and all well received with respect and 
 admiration.  Everyone freely giving and responding to any quest for knowledge 
 or help.  Sometime just sharing an experience.  All, as interesting to read 
 as anything in a library.  I could not in my worst nightmare think badly of 
 anyone on the list, and so that is my Christmas gift to myself.
 
 Merry Christmas to all.
 
 Steve
 
 Yorktown, VA
 
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Re: life before clocks

[Kevin Karney]

Brent

This is a HUGE series of questions you have raised. Here are a few 
observations

Remember that clocks for the masses are very very new (mid to late 19th C).

Throughout most of civilization, there were 12 unequal hours between sunrise 
and sunset. The marked time on a sundial was an event-indicator rather than 
time as we now (seem to) understand it.

Even in early days, sundials were mainly the preserve of the rich, the 
astronomers, the intellectuals and the city fathers.

Here are some quotes...
Aristophanes 446 – ca.386 BC from his play the 'Assembly of Women' where women 
took over the government..
When your shadow is ten times the length of your foot,
all you have to do is… ... perfume yourself and come to dinner 

Plautus - 254 – 184 BC
The Gods damn the man who first discovered the hours and - yes - set up a 
sundial here which has smashed the day into bits.
When I was a boy, my stomach was the only sundial, by far the best and truest 
compared to these: it used to warn me when to eat.

St Leofric's Missal 9 - 11C AD
Martius et October, Hora Tertia et Nona, Pedes XIII, Hora VI Pedes VII
= the length of your shadow in March  October is 13 feet at the 3rd  9th Hour 
(unequal hours after sunrise) and 7 feet at noon
(with 5 similar rules for the other months - the hours being - unsurprisingly 
the times of the Benedictine Terce, Sext, None prayer times)

William Chaucer ca 1343 - 1400
It was four o’clock according to my guess
Since eleven feet, a little more or less,
My shadow at the time did fall, considering that I myself am six feet tall.

Accurate time (as we now understand it) grew primarily out of the needs of 
navigators - and with that need,  clocks really came into their own. But where 
astronomers were not available to give accurate time through noon balls or 
cannons. Clocks were set using sundials with the equation of time correction. 
It was the railways - and the advent of the telegraph to transmit accurate 
astronomer's time - that introduced national mean time and heralded the end of 
the serious timekeeping life of the sundial.

It's a fascinating subject

See also some in text comments below...

best regards
Kevin Karney


On 19 Nov 2010, at 21:41, Brent wrote:

 I wonder what life was like before mechanical clocks.
 
 I suppose your day was less structured than ours are today.
 Maybe to work at sunrise, go home at sunset.
 Eat when you are hungry, sleep when you are tired.
 
 I wonder how many people used sundials? Was it a common thing to have?
 Was it a necessity?
 
 How did everyone show up on time for a 9pm Opera?
 
 What was the accurate time of day good for back then?
 
 Before mechanical clocks you probably wasted a lot of time waiting for people 
 or events.
 
 Who cared about accurate time, and why?
 
 Churches?  Mosques - St Benedict set the time of prayer - followed in 
 principle - my the Muslims. The Christians were more interested in an 
 understandable more-or-less repeatable regular structure i.e. event markers. 
 While the Muslims were more concerned with a precise timing of their prayer - 
 hence their complex timing of prayer based (once more) on shadow lengths (Asr 
 prayer begins when the length of any object's shadow equals the length of the 
 object itself plus the length of that object's shadow at noon - different but 
 comparable definitions by different muslim schools) and superseded by 
 sophisticated sundials
At night time, monks did not waste money on such things as expensive candle 
clocks to dictate the timing of Compline. One particular monk was told to wake 
up in the middle of the night and wake the others. He was not to be fed too 
much in the evening unless his stomach troubled him and his time keeping 
regularity was upset

 Armies?

 Courts? - They did not concern themselves so much with the 'when' as the how 
 long - for which they used water clocks (clepsidra). The judge in ancient 
 times would decide if a case was legally interesting enough to warrant a 
 large or small clepsidra. Both prosecution and defence has until time ran 
 out to make their case. Prostitutes used a similar strategy.

 Scientists? - Yes - astronomers. Ptolemy 150AD understood exactly all about 
 the equation of time. He needed that understanding - not to tell the time - 
 but to fit his theories of lunar movements

 Governments? 

  
 Sailers? - Needed for Longitude calculations
 
 Sundials became very sophisticated, but why? To calibrate the clocks in the 
 absence of time signals
 
 thanks;
 brent
 
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Re: Sundial Information

[Kevin Karney]

I'm for Harriet's interpretation Athene, her owl and the meaning of gnomon
K

On 19 Nov 2010, at 16:03, Brad Lufkin wrote:

 I suspect there's no relationship. The publishers of the humor magazine were 
 probably making an oblique reference to the owl of Athena, which is a symbol 
 of wisdom. A bit sly, but also a bit self-congratulatory (but this is a 
 college humor magazine, not Dean Swift).
 Brad
 
 On Fri, Nov 19, 2010 at 10:43 AM, John Carmichael jlcarmich...@comcast.net 
 wrote:
 Hi Dialists:
 
  
 I received this intriguing letter from Ohio State University.  The writer 
 talks about an old publication called “The Sundial”.  And then asked me if I 
 am aware of any relationship between sundials and owls!  I am not aware of 
 any association between the two.  I asked him to send me any photos of this.  
 Meanwhile, I’m asking you guys if you have seen any relationship between owls 
 and sundials.
 
  
 Thanks!
 
  
 I’ll forward your answers to him, or you can write him directly.
 
  
 John
 
  
  
  
 From: Nathan Varrone [mailto:nathanvarr...@gmail.com] 
 Sent: Friday, November 19, 2010 1:20 AM
 To: jlcarmich...@comcast.net
 Subject: Sundial Information
 
  
 Dear John Carmichael,
 
  
 I am currently reviving a humor magazine titled The Sundial at The Ohio State 
 University. In old issues of The Sundial, I often see an owl on top of the 
 drawn images of sundials. Is there any association with owls and sundials 
 that you would know of?
 
  
 Thanks so much for your time, we may do business with you in the future!
 
  
 Best,
 
 -- 
 Nathan L. Varrone 
 The Ohio State University
 Associate Director, 8th Floor Improv
 President, The Sundial
 
 
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Re: What can be calculated with a sun dial?

[Kevin Karney]

This list - together with all the additions - is great !

But, it would be nice to see which of the many items can be done well by a 
sundial and how many items would be a 'stretch'. To find the moment of equinox 
- for example - is theoretically possible - but in actuality is not realistic 
since the Sun's declination is changing so slowly at those times: (a problem 
the astronomers of antiquity struggled with).  Equally, I think one would be 
hard pressed to find aphelion  perihelion from a dial - except in a very 
indirect fashion.

But let's get the list complete !

Best regards
Kevin Karney

On 16 Nov 2010, at 21:38, Jos Kint wrote:

 Dear sun dialists,
  
 What can be calculated with a good sun dial? Here is a list of 19 topics. Can 
 you add some more items?
 1. The hour of the day
 2. The day of the year.
 3. The solar altitude.
 4. The solar azimuth.
 5. The longitude of the sun dial.
 6. The latitude of the sun dial.
 7. The moment of the equinoxes
 8. The moment of the solstices.
 9. The length of the tropical year
 10. The equation of time
 11. The excentricity of the earth orbital around the sun.
 12. The obliquity of the eclips
 13. A compass function
 14. The declination of the sun.
 15. The moment of the perihelion
 16. The moment of the aphelion
 17. The moment of the next sun set
 18. The Babylonic time
 19. The Italian time
  
  
 Jos Kint
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Not really to do with Sundials, but some good shadows...

[Kevin Karney]

Mapping during 600 years anniversary of the astrological tower clock situated 
at Old Town Square in center of Prague.

This was projection onto the front of the church

http://vimeo.com/15749093

Best regards
Kevin Karney---
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Re: Creating .EPS file format for sundials..

[Kevin Karney]

Hi Roderick

If you have the latest version of OpenOffice, all you have to do is to open 
your document, then go to the menu item File, then select Export, then 
click on the pop-up item File Type, then select EPS, then you'll get a 
dialog box with various options - choose TIFF/Level 2/Colour/None. That's 
all

If your sand blaster cannot read the file produced, try different options in 
the last dialog box.

Hope that works for you. If not, let me know and I'll think again
Best regards
Kevin Karney

On 13 Jul 2010, at 07:35, R Wall wrote:

 Hi all,
  
 I want to design a sundial that will be sand blasted onto glass. Our local 
 glass sandblaster say they need the sundial image to be in the Encapsulated 
 PostScrip file format (filename.EPS).
  
 I have OpenOffice.org Draw software. It won't save the drawing with the 
 extension of .EPS. Is there a converter that will convert OpenOffice.org Draw 
 into .EPS files. This may not be easy as it needs to use vectors in the .EPS 
 file.
  
 Will any of the Sundial Drawing software save the results in .EPS file format.
  
 Or is there a better way to generate Encapsulated PostScrip files for 
 sundials.
  
 Thanks for your help,
  
 Roderick Wall.
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Re: Burnsville Sundial article

[Kevin Karney]

This is a great dial !

I love the EoT representation.

Good pictures of the dial at 
http://quilttrailswnc.org/sundial.html

Best regards
Kevin Karney


On 17 Jun 2010, at 03:21, Bob Hampton wrote:

 Greetings,
 The Charlotte Observer recently ran a short article in their Science and 
 Technology section about our Burnsville Quilt Block Sundial.  Here's the link 
 to the online article:  
 http://www.charlotteobserver.com/2010/06/07/1482630/a-timely-lesson-on-our-solar-system.html
 
 Bob Hampton
 
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Re: The Jacobs Glass Sphere Dial

[Kevin Karney]

Hi Fabio
As you say, this is not really a sundial, but a sundial recorder of the 
Campbell-Stokes type. See http://en.wikipedia.org/wiki/Campbell-Stokes_recorder.

If you get the paper strip - which you must change each day - correctly 
aligned, it can of course be used as a sundial. Also by adjusting the strip 
according to the EoT it can be a mean time dial.

Before electronics took over, every meteorological station had one of these 
recorders. Every day the paper strip - which was made of special card so that 
it would only blacken and not completely burn - was changed and the length of 
blackened line was measured to give the hours of sunshine on the previous day. 
The paper was designed to burn right through if there was full sunshine, but 
just to leave a mark if the sun was only hazy. (I did this every day for three 
years at school when around 14 years old - it was a very boring job)

Because the focal length of a glass sphere is so short, such instruments are 
not great as sundials. A greatly improved version can be made with a long focal 
length sphere as invented by Prof Julian Chen of Columbia University. See NASS 
Compendium 14(4) pp 5-8 (Dec 2007). This uses a hollow lucite sphere filled 
with a copper sulphate solution which gives a cool non-burning blue image. This 
is very difficult to fabricate.

Best regards
Kevin Karney

 
On 8 Jun 2010, at 17:01, Fabio Savian wrote:

 hi all,
  
 today I find a new sundial on Sundial Atlas like the one you described 
 www.sundialatlas.eu/atlas.php?so=IT1611
  
 Riccardo Anselmi, a diallist of Aosta Valley in Northern Italy, registered it 
 with some info. The sundial was in the balcony of a thermae in Saint-Vincent. 
 The glass sphere focused the Sun beam on a paper strip placed on the 
 equatorial ring; The beam burned the paper so that it was possible to 
 evaluate the period of sunstroke and the local hour. The photo was taken in 
 the eighties before the sundial was stolen.
  
 SA is able to classify this sundial as 'stolen' to contribute to its finding 
 or to discourage these events.
  
 ciao Fabio
  
  
 Fabio Savian
 fabio.sav...@nonvedolora.it
 Paderno Dugnano, Milan, Italy
 45° 34' 10'' N   9° 10' 9'' E
 GMT +1 (DST +2)
 - Original Message -
 From: John Carmichael
 To: 'Fred Sawyer'
 Cc: sundial@uni-koeln.de
 Sent: Monday, June 07, 2010 6:17 PM
 Subject: The Jacobs Glass Sphere Dial
 
  
 Hello Fred (cc Sundial List):
  
 I enjoyed reading about the Jacobs glass sphere dial in the recent issue of 
 the Compendium as I have not been up to the mountain and have not seen it in 
 person. I had forgotten that I had discovered the Jacobs glass sphere dial at 
 Kitt Peak several months ago while searching for dials on Flickr.  A Flickr 
 non-dialist photographer  took two EXCELLENT photographs of it and gave me 
 permission to post them at: 
 http://www.advanceassociates.com/Sundials/Stained_Glass/sundials_EGP.html  
 (Dial # 435 at the bottom of the page) I knew it looked familiar!  There are 
 several similar glass sphere dials on our webpage, but this is one of the 
 best.  Here are the two photos taken by the photographer, Matt Anderson. © 
 All rights reserved.  Unlike the cloudy overcast photo given to you by L.  
 B. Graver, these photos clearly show the focused spot of light.
  
 See: 
 http://www.advanceassociates.com/Sundials/Stained_Glass/sundials_files/New%20Files/Originals/SGS_435a.jpg
 and
 http://www.advanceassociates.com/Sundials/Stained_Glass/sundials_files/New%20Files/Originals/SGS_435b.jpg
  
 I must go visit this dial in person because I have several questions about 
 it. 
  
 First, if you look closely at the spot of light it is NOT a small point of 
 light as seen in Campbell-Stokes recorders.  It looks wider (about ½ inch). 
 I’m wondering if professor Jacobs did this on purpose by placing the 
 projection screen closer to the glass sphere than the focal point distance. 
 As we all know, the sunlight focused by a glass ball can get VERY HOT!  It 
 burns paper and fingers (Once I accidentally placed a glass sphere gnomon 
 counterweight from one of my cable dials on an outdoor sofa and it burned a 
 hole in the cushion!)  If Jacob’s projection screen is of Plexiglas or 
 acrylic plastic, then a sharply focused point of light would melt it or might 
 even catch it on fire.  So perhaps Jacobs intentionally placed it closer to 
 the sphere to spread out the light and avoid the hot temperatures.
  
 If the projection screen is made from glass, it wouldn’t melt or catch on 
 fire, but it might crack from the high temperature differential.  So placing 
 the screen out of focus would prevent this.
  
 In any case, since it appears that the focused spot of light is out of focus, 
 this would affect the precision of the time readings.
  
 So the big questions are:
 What is the projection screen made from?
 And why does the focused light seem too big and out of focus?
  
 Jim Tallman and I have discussed this dial and Jim also