Re: Old Egyptian sundials

[Bill Gottesman]

Dear List-Members,

Some of you may know I bought Richard Schmoyer's 
original Sunquest sandcast patterns last spring. I now have several 
completed dials for sale, both in Aluminum and in Bronze. If you would 
like to see them, visit www.precisionsundials.com, and 
follow the links to the Schmoyer Sunquest. Unmachined casting sets are 
also available for do-it-yourselfers. One Bronze Sunquest that should be 
available for public viewing this spring is being delivered to the Perkins 
Observatory in Delaware, Ohio.

Bill Gottesman

Re: South Vertical Declining dial

[Bill Gottesman]

Dear Dave,

Your calculations are close, but being 1.9 degrees east of your meridian, this 
makes your dial run fast by 7 minutes, 36 seconds, not including the equation 
of time.  Each degree of longitude from the meridian affects the dial by 4 
minutes.

So, your dial should be 7' 36 fast by your location, plus 3' 44 fast for what 
you give as the EoT, for a total of 11' 20 fast on may 13.

If your dial is accurately made, and you are able to read the sundial time to 
within a few seconds (you may be able to do this if you know how to use a 
shadow sharpener), you can calculate how misaligned your dial or wall is 
using www.precisionsundials.com/sundialalign.exe .  It works best near the 
solstices, so next month would be the ideal time to try it out.

Bill Gottesman
www.precisionsundials.com


- Original Message - 
  From: [EMAIL PROTECTED] 
  To: sundial@uni-koeln.de 
  Cc: [EMAIL PROTECTED] 
  Sent: Monday, May 14, 2007 7:10 PM
  Subject: South Vertical Declining dial


  Dear Sirs: Here's my problem. When my south vertical declining dial reads 
11:00 my watch (set by Click here: The official US time ) reads 10:50, when it 
reads 12:00 my watch  reads 11:50 at 2:00 the watch reads 1:50 and at 3:00 the 
watch reads 2:50. The location of the dial is at 33.44N and 118.1W, the 
declination of the wall is between .1 degree and 2.7 degrees west of south 
depending on the accuracy of the measurement. I used two methods one from 
www.precisionsundials.com/walldeclination.exe which produced the .1 degree and 
the other from Click here: Sundial Sculptures by John Carmichael, Jr. which 
produced 2.7 degree based on the measurements I gave him. John was extremely 
helpful and even sent dial plate with gnomon measurements. The times above were 
taken on 5/13/07. The standard time meridian in my area is 120 degrees, me 
being at 118.1 = equals approximately 4 minutes and the EOT on the 13th is 3:44 
(from table A.1 in Sundials - Their Theory and Construction, by Albert E Waugh, 
that's still only adds up to  7:44. If this is the wrong forum for this kind of 
problem please let me know, any and all help is appreciated.
  Thanks Dave Koller   










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A fast Sundial (apologies if this is a duplicate mailing)

[Bill Gottesman]

I recently built this fast sundial.  I think you will get a kick out of it.  
View it on this private web-page for sundial list readers:

www.precisionsundials.com/sundial_list.htm

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

Re: A very interesting dial

[Bill Gottesman]

Fascinating.  Does anyone know it the analemmas were placed after observing the 
movement of the sun, or before?  i.e., how was it done?  And, is there a 
focusing lens involved?  And if so, how do they dealt with focusing it over 
such a variable distance?

-Bill G.
  - Original Message - 
  From: Robert Terwilliger 
  To: 'Sundial Mailing List' 
  Sent: Sunday, May 20, 2007 1:32 PM
  Subject: A very interesting dial


  A new and very interesting, perhaps unique, dial has been added to the NASS 
Sundial Register. The dial is delineated on the inside walls of a purposely 
built tower. Indications include analemmas as well as altitude and azimuth. 

  Go to Colorado, then scroll down to Englewood #T003

  http://sundials.org/registry/

  Bob Terwilliger
  NASS Webmaster


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Re: Non-terrestrial sundials

[Bill Gottesman]

What a hoot.  Thanks for putting those photos on the internet.  It works 
like a ring dial on steroids.  Very cool.

-Bill G.



- Original Message - 
From: fer de vries [EMAIL PROTECTED]
To: J. Tallman [EMAIL PROTECTED]; Sundial List 
[EMAIL PROTECTED]
Sent: Sunday, October 14, 2007 11:11 AM
Subject: Re: Non-terrestrial sundials


 Jim and others,

 I know about a sundial on board of a passengers ship.
 I posses a photo-copy of small booklet about the dial and its use.

 The ship is the MS Oranje, built in 1938/39.
 About the ship and her history have a look at:
 www.ssmaritime.com/oranje.htm

 The ship ended her life in 1979 as Angelina Laouro, when it sunk.


 On board of MS Oranje was a sundial.
 The priciple is based on the universal ring dial although it is
 constructed as a cresent dial.
 The dial was set to the latitude, the cresent was set to the date.
 With knobs the dial could be placed level.
 The foot of the dial was on a compass with a scale of 360 degrees.
 Turn the dial until the shadow of the endpoint of the cresent falls on the
 central line of
 the hourscale.
 The dial then is north-south oriented and the time and azimut of the 
 ship's
 course could be read.
 The time's scale was for local suntime.

 I don't know if the instrument was placed on a cardanic support like is 
 seen
 in Mayall page 153, mentioned by Peter Mayer.

 The dial wasn't meant as an instrument for the sailors but for the
 passengers to play with and wonder about the relations of the course of
 the sun, of the ship and the time.

 The dial was designed by W.G. ten Houte de Lange, adjunct director of the
 Zeiss planetarium in The Hague, now not longer excisting.

 He also wrote the booklet about the dial in or around 1939.

 Two black and white photos from the booklet are temporaly placed at:

 http://www.de-zonnewijzerkring.nl/tijdelijk/photos.htm


 Best wishes, Fer.


 Fer J. de Vries

 De Zonnewijzerkring
 http://www.de-zonnewijzerkring.nl

 Molens
 http://www.collsemolen.dse.nl

 Eindhoven, Netherlands
 lat.  51:30 N  long.  5:30 E

 - Original Message - 
 From: J. Tallman [EMAIL PROTECTED]
 To: Sundial List [EMAIL PROTECTED]
 Sent: Saturday, October 13, 2007 4:16 PM
 Subject: Non-terrestrial sundials


 Hello All,

 Has anyone ever seen a sundial specifically designed for use on a boat
 or ship?

 I realize that there are obvious issues re: movement and variable
 location, but I thought it might be an interesting question for the list
 to consider from the historical perspective...


 Best,

 Jim Tallman
 www.artisanindustrials.com
 [EMAIL PROTECTED]

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Re: Mystery object

[Bill Gottesman]

According to www.campbellsci.ca/Museum_Radiation_1_F.html , it is a 
Campbell-Stokes sunshine recorder.  Apparantly, it is still in use, and 
still available.
-Bill


- Original Message - 
From: Dave Bell [EMAIL PROTECTED]
To: Frederick Jaggi [EMAIL PROTECTED]
Cc: Sundial Sundial List sundial@uni-koeln.de
Sent: Tuesday, October 16, 2007 10:32 PM
Subject: Re: Mystery object


 Frederick Jaggi wrote:
 Hi Everyone:

 Here's a mystery object from the current Skinner auction. Could it be
 sundial related?
 http://www.skinnerinc.com/asp/fullCatalogue.asp?salelot=2383++93
 +refno=++691521saletype=
 Fred Jaggi
 ---

 Or, even a sundial itself!
 First, a short link, that won't get trashed by email programs:
 http://tinyurl.com/3yqcjk

 It's a crystal globe that acts as a lens to focus a sun spot onto the
 curved brass curved.
 The plate is engraved for hour lines and declination curves...

 Dave
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Re: Mystery object in 3-D

[Bill Gottesman]

I stumbled across a cool 3-D view of a campbell stokes recorder here: 
http://www.ems.psu.edu/~fraser/qtvr/ssr.html

You have to permit the Active-X control to view it

-Bill G. 
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Re: Does Refraction Affect Azimuth? / Re: sundial Digest, Vol 24, Issue 17

[Bill Gottesman]

Mashallah,

I believe you are correct about azimuth and time of transit being unaffected by 
refraction.

Astronomical Algorithms by Jean Meeus has a good section on calculating 
effects of refraction and the sun's semi-diameter.  Also a valuable section 
about how to correct for the effects of Nutation.  I'm not so sure about the 
other topics you mention.  I would guess parallax of the sun from the 
perspective of the earth's diameter is covered in surveying books, or perhaps 
one of the astronomical trigonometry books by Smart.

-Bill Gottesman
  - Original Message - 
  From: Mashallah Ali-Ahyaie 
  To: sundial@uni-koeln.de 
  Sent: Thursday, December 27, 2007 4:24 AM
  Subject: Does Refraction Affect Azimuth? / Re: sundial Digest, Vol 24, Issue 
17


  Dear Mr Gianni Ferrari,

 Greetings, happy new year and Merry Christmas to you and all members.

 As I recall, the azimuth of a body and its time of transit are not 
affected by refraction. Please kindly do comment.

 Also, I would like to have a good and applied article on astronomical 
corrections (Refraction, Parallax, Dip of Horizon and Semi-Diameter.) I wonder 
if any respectful member could help. 

  Best regards,

  Mashallah Ali-Ahyaie


  On Dec 26, 2007 2:30 PM, [EMAIL PROTECTED] 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 
   [EMAIL PROTECTED]

You can reach the person managing the list at
   [EMAIL PROTECTED] 

When replying, please edit your Subject line so it is more specific
than Re: Contents of sundial digest...


Today's Topics:

  1. R: Re: Azimuth of Sunrise - Sunset ( [EMAIL PROTECTED])


--

Message: 1
Date: Tue, 25 Dec 2007 22:58:32 +0100 (GMT+01:00)
From:  [EMAIL PROTECTED] [EMAIL PROTECTED]
Subject: R: Re: Azimuth of Sunrise - Sunset
To: sundial@uni-koeln.de 
Message-ID: [EMAIL PROTECTED]
Content-Type: text/plain;charset=UTF-8


And the air refraction ?

Because of refraction, the sun is already 
below the horizon when we observe
the upper limb kiss the horizon. In
this moment the altitude of the Sun?s center is  about
?(34+14) = -48?
(the refraction at 0? degree is about 34?)
The Azimuth of the point 
where we begin to see the Sun (limb) is then different from the
theoretical and geometrical value, also if the differences are small at
mean latitudes.

 With Lat = 45 on  Winter Solstice,  the Azimut of the 
Sun?s limb (when it appears)  is about 56.8 degree ; the Azimuth of the
Sun?s center 56.4? and the theoretical Azimuth 55.8?.
The differences
increase when Latitude increases.
With Lat.= 66?. the Sun?s limb 
appears with an Azimuth about 7 degree more than the theoretical value
(18.8 and 11.9?)

My best wishes for a sunny New Year !
Gianni Ferrari




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End of sundial Digest, Vol 24, Issue 17
***




  -- 
  Mashallah Ali-Ahyaie 


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Re: Does Refraction Affect Azimuth? / Re: sundial Digest, Vol 24, Issue 17

[Bill Gottesman]

Warren, It is good to hear from you.  And now I know at least one person was 
awake during my talk.

I think you are exactly right.  

Did I misinterpret Mashallah's question?  By Time of Transit, I took that to 
mean when the sun or a star passes the north-south meridian overhead, and not 
the sunrise or sunset.  Frankly, I forgot that this question was asked in the 
context of the solstice sunrise at Newfane.  Refraction does not affect azimuth 
at any given time, but it affects the azimuth of sunset because it also affects 
the time of (apparent) sunset.

-Bill
   - Original Message - 
  From: Warren Thom 
  To: Bill Gottesman ; Mashallah Ali-Ahyaie ; sundial@uni-koeln.de 
  Sent: Thursday, December 27, 2007 12:47 PM
  Subject: Re: Does Refraction Affect Azimuth? / Re: sundial Digest, Vol 
24,Issue 17


  Hi Bill,

  If I recall your comments at the NASS meeting correctly,  while azimuth might 
be unaffected by refraction, because the real time of sunset  is later due to 
refraction, the azimuth at a later time needs to be calculated. That is, for us 
at North latitudes the sunset is further North than a normal calculation of 
sunset would give.  Assume no objects on the horizon.   Did I miss something?

  Warren


- Original Message - 
From: Bill Gottesman 
To: Mashallah Ali-Ahyaie ; sundial@uni-koeln.de 
Sent: Thursday, December 27, 2007 11:12 AM
Subject: Re: Does Refraction Affect Azimuth? / Re: sundial Digest, Vol 
24,Issue 17


Mashallah,

I believe you are correct about azimuth and time of transit being 
unaffected by refraction.

Astronomical Algorithms by Jean Meeus has a good section on calculating 
effects of refraction and the sun's semi-diameter.  Also a valuable section 
about how to correct for the effects of Nutation.  I'm not so sure about the 
other topics you mention.  I would guess parallax of the sun from the 
perspective of the earth's diameter is covered in surveying books, or perhaps 
one of the astronomical trigonometry books by Smart.

-Bill Gottesman
  - Original Message - 
  From: Mashallah Ali-Ahyaie 
  To: sundial@uni-koeln.de 
  Sent: Thursday, December 27, 2007 4:24 AM
  Subject: Does Refraction Affect Azimuth? / Re: sundial Digest, Vol 24, 
Issue 17


  Dear Mr Gianni Ferrari,

 Greetings, happy new year and Merry Christmas to you and all members.

 As I recall, the azimuth of a body and its time of transit are not 
affected by refraction. Please kindly do comment.

 Also, I would like to have a good and applied article on astronomical 
corrections (Refraction, Parallax, Dip of Horizon and Semi-Diameter.) I wonder 
if any respectful member could help. 

  Best regards,

  Mashallah Ali-Ahyaie


  On Dec 26, 2007 2:30 PM, [EMAIL PROTECTED] 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 
   [EMAIL PROTECTED]

You can reach the person managing the list at
   [EMAIL PROTECTED] 

When replying, please edit your Subject line so it is more specific
than Re: Contents of sundial digest...


Today's Topics:

  1. R: Re: Azimuth of Sunrise - Sunset ( [EMAIL PROTECTED])


--

Message: 1
Date: Tue, 25 Dec 2007 22:58:32 +0100 (GMT+01:00)
From:  [EMAIL PROTECTED] [EMAIL PROTECTED]
Subject: R: Re: Azimuth of Sunrise - Sunset
To: sundial@uni-koeln.de 
Message-ID: [EMAIL PROTECTED]
Content-Type: text/plain;charset=UTF-8


And the air refraction ?

Because of refraction, the sun is already 
below the horizon when we observe
the upper limb kiss the horizon. In
this moment the altitude of the Sun?s center is  about
?(34+14) = -48?
(the refraction at 0? degree is about 34?)
The Azimuth of the point 
where we begin to see the Sun (limb) is then different from the
theoretical and geometrical value, also if the differences are small at
mean latitudes.

 With Lat = 45 on  Winter Solstice,  the Azimut of the 
Sun?s limb (when it appears)  is about 56.8 degree ; the Azimuth of the
Sun?s center 56.4? and the theoretical Azimuth 55.8?.
The differences
increase when Latitude increases.
With Lat.= 66?. the Sun?s limb 
appears with an Azimuth about 7 degree more than the theoretical value
(18.8 and 11.9?)

My best wishes for a sunny New Year !
Gianni Ferrari




--

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Re: Advice wanted, on 'Analemmatic' sundial orientation

[Bill Gottesman]

Nice job.  Original, adaptable.  I suspect it can be modified to apply 
to a larger scope of dials than just analemmatic.  Not sure the public 
would go for it aesthetically, but I admire the concept.

-Bill Gottesman

John Lynes wrote:
 I'm grateful for the generous reception you gave to my last contribution to 
 this thread.  Here belatedly is another possible solution, less impractical 
 but more complex than my last effort.

 Imagine a North-South meridian line on flat ground.  On this line place a 
 thin flat vertical mirror - essentially a vertical reflective slit - a few 
 feet above the ground and pivoted to rotate about a vertical axis through the 
 mirror and the meridian.  When the sun shines, a visitor is asked to turn the 
 mirrored slit so that the sun's reflection falls along the meridian line.

 Straight below the slit, locked to the same vertical axis, is a small 
 horizontal analemmatic sundial, a few inches across, placed so that the axis 
 of rotation of the assembly coincides with the calendar date-point on the 
 analemmatic dial, and the major axis of the analemmatic dial's ellipse is 
 parallel to the plane of the mirror.  The direction of the meridian line 
 indicates the solar time on the (modified, see below) face of the analemmatic 
 dial.

 The azimuth of the mirror, measured from the meridian, would be only half the 
 azimuth of the sun, so the hour markings on the analemmatic dial would need 
 adjusting, e.g. the 1pm mark would be relabelled 2pm (sorry, 10.am).  They 
 would run anti-clockwise, and would of course be reversed from north to south.

 A groundsman would have to keep the mirror polished, and realign the 
 date-point with the axis of rotation perhaps once a week.  He might fix a 
 different dial for daylight saving.

 Now comes the nifty bit!  Mr Phillips is not forced to accept a North-South 
 meridian line.  He could commission a line parallel to his main driveway, for 
 aligning the reflection of the sun.  A small fixed North-South marker would 
 still indicate the time on the analemmatic dial.  I leave it to the 
 heavyweights to recalculate the hourly markings on the dial face.

 Alas the gnomon is no longer human, but the device would be interactive, 
 instructive and, I daresay, unprecedented.

 Apologies for a disgracefully late entry!

 John Lynes


 -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]

 Dear Sundial Experts,  
 I have recently joined this Mailing List, and hope that any members will be 
 able to give me some assistance on the following situation.
 Our local Stately Home (Kentwell Hall, Long Melford, Suffolk) is 
 considering installing an Analemmatic sundial, as a new interactive 
 attraction for visitors - but we are getting 'conflicting' advice, on whether 
 this 'Human Sundial' will work in the way we want it to.  We have been in 
 discussion with Modern Sunclocks (apparently the acknowledged 'experts' for 
 these features), who have told us that its central scale of dates must be 
 aligned North/South - plus that hour markers must be correctly positioned on 
 an elliptical ring, and which would lie on the Northern side of that scale of 
 dates.
 Photographs on their website ( www.sunclocks.com ) confirm this.
 However, our 'Director of Operations' (Mr Phillips) absolutelyINSISTS that he 
 wants the scale to run exactly parallel with ourmain driveway - on a compass 
 bearing which is about 162 degreesfrom North, with the hour points placed on 
 its Southern side.He also wants the hour points to form an exact semi-circle, 
 andnot be elliptical in shape.  Mr Phillips refuses to accept thathe cannot 
 arbitrarily position the Human Sundial feature as hewishes, and says that it 
 must be possible to create this so thatit could then align with the existing 
 layout of buildings/paths.
 Can anyone on this Mailing List tell me whether it is possible toinstall a 
 Human Sundial to fit any existing orientations, (withappropriate 
 re-calculation of its component parts) - or, if not,just confirm that it must 
 be as Modern Sunclocks have told me.
 I can then show the 'weight of evidence' to Mr Phillips.  BecauseKentwell 
 Hall is a well-known Stately Home (open to the public),we should not want to 
 become a 'laughing stock' by installing afeature which does not work - 
 despite Mr Phillips assurance thatall types of sundial can be adjusted to 
 work, in any location.
 Looking forward to all comments (to this List, or sent privately).  
 Sincerely,  Alison Shields.

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Re: How to engrave marble?

[Bill Gottesman]

Very fine lines can be etched with an abrasive blaster.  Silicon carbide 
is the best blasting material, but aluminum oxide (less expensive) also 
works well.  I hire a sign maker to blast the granite (and occasionally 
marble) stones for my Sawyer Equant sundials.  The lines are about .040 
wide and .005 deep, and paintfill nicely with the mask still in place.  
The mask is a thin (sign) vinyl, cut on a signmaker's vinyl cutting 
machine from an adobe illustrator file.  It costs about $40 per stone.  
If you do it yourself, be meticulous about eye and lung protection -- 
This can be hazardous.  Photos on my website.

I'm sure you could also use a rotary dremel-like tool with an 
inexpensive diamond ball bit.  John Carmichael engraves his stone dials 
this way.  He gave a demonstration at his home a few years back, and 
this method was very effective and did not appear too difficult.  He 
glues the design right against the stone, and cuts right through the 
paper (or vellum?).  He has a hose trickle water over the cutting 
surface to cut down on dust and prolong tool life.  His website is 
www.sundialsculptures.com

Bill Gottesman
www.precisionsundials.com

Ricardo Cernic wrote:
 Hi dialist fellows!

 I'm considering to make a sundial with marble. Does anyone have some tips in  
 how to engrave this type os material? I've already manually engraved slate 
 with nails of different diameters, but when I try the same process with 
 marble I do not get neat lines.

 What I'm looking for is a process that can be done at home without machinery. 
  Chemicals are an option.

 Thanks,
 Ricardo
 São Paulo - Brazil


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Re: Earth eccentricity

[Bill Gottesman]

I am not recalling the details, but a few years ago I read an excellent 
book The Sun and the Church, about the meridian lines placed in a few 
cathedrals in Europe, to help predict the date of Easter.  Apparently, 
the information gathered from these giant and precise meridian lines was 
sufficient to eventually allow renaissance scientist/mathematicians to 
conclude that the Earth's orbit was elliptical, and not circular, and 
that the sun, not earth, was at the center of the solar system.  The 
church scientists had to present these conclusions as hypothetical, 
because of Galileo's then recent confinement for publicly expressing the 
same opinion.  The irony is that the very same meridian line that was 
built to support church doctrine (Easter) was found to disprove other 
church doctrine (Ptolemaic solar system).

-Bill Gottesman

Jos Kint wrote:
 Hello all,
  
  
 I am looking for some help in observing the earth's 
 orbital eccentricity, just by using my sun dial. Who gives me some 
 hint? With my vertical 2,5 meter by 1,5 meter sun dial I can measure 
 the local solar time with an accuracy of  less than 60 seconds.
  
 Jos Kint, Belgium
 

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Rapid Prototyping for sundial parts

[Bill Gottesman]

I am hoping the sundial mailing list may be able to give me suggestions 
on affordable software for design and rapid-prototyping.  I want to be 
able to design and rapid-prototype small sundial models or parts.

I was about take a university course in Solidworks, because for $100 you 
can buy a 2 year license for a working full featured student version, 
EXCEPT that 1) It will not export a usable rapid-prototype file, and 2) 
It will not export a Solidworks file for use on a commercial Solidworks 
program.  In this manner, Solidworks makes sure that nothing of 
commercial value can be created on the inexpensive student version, and 
that for commercial purposes, you have to use/buy the commercial 
version, which starts at $4,000.  I decided not to invest my time in the 
Solidworks course.

But I now wonder if there is a decent, more affordable program that lets 
hobbyists and small businesses design 3-D models, and allows you to 
export them in a file format suitable for rapid prototyping?

-Bill Gottesman
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Re: Rapid Prototyping for sundial parts

[Bill Gottesman]

I want to thank all contributors for their ideas/recommendations.  I 
have looked a bit into Google Sketch-up, but do not see that it can 
export a .stl file for rapid prototyping.  At present I am going to try 
Alibre, which has a free version which seems powerful enough to do all I 
need.  The full version (about $1,000) is only 1/4 the price of 
Solidworks, if needed, and is available greatly discounted to students 
(I am enrolled at a local university as a continuing education student).

-Bill


 
 I am hoping the sundial mailing list may be able to give me suggestions
 on affordable software for design and rapid-prototyping.  I want to be
 able to design and rapid-prototype small sundial models or parts.

 I was about take a university course in Solidworks, because for $100 you
 can buy a 2 year license for a working full featured student version,
 EXCEPT that 1) It will not export a usable rapid-prototype file, and 2)
 It will not export a Solidworks file for use on a commercial Solidworks
 program.  In this manner, Solidworks makes sure that nothing of
 commercial value can be created on the inexpensive student version, and
 that for commercial purposes, you have to use/buy the commercial
 version, which starts at $4,000.  I decided not to invest my time in the
 Solidworks course.

 But I now wonder if there is a decent, more affordable program that lets
 hobbyists and small businesses design 3-D models, and allows you to
 export them in a file format suitable for rapid prototyping?

 -Bill Gottesman
 ---
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Re: Preventing Rod Gnomon Bending

[Bill Gottesman]

Dangerous territory for me; I am not an engineer.

That said, see attached pdf.  Could a cable or rod strung internally in 
the hollow pole/gnomon be placed under tension, causing the pole to bow 
upwards against gravity?  The rod or cable could have a turnbuckle to 
make the tension adjustable, until it equally counteracts the droop from 
gravity.


Must do some experimenting first, so that it does not bend pole 
unexpectedly sideways, or helically.


-Bill


Carmichael Pole.pdf
Description: Adobe PDF document
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YouTube videos

[Bill Gottesman]

Hello list members,

I recently placed all (5) of my sundial related videos on YouTube, which 
makes them more easily accessible and compatible with different 
computers.  Some of you have seen them before.  They can be accessed 
either by typing precision sundials into the YouTube search box, or 
directly from my software page www.precisionsundials.com/software.htm .  
Please note, this is not a request for customers or new business; I am 
busy enough already.

The movies are:
-45 second video of single focusing Renaissance sundial (Truth in 
reporting -- dial was adjusted to read more accurately than typical).
-45 second video of double focusing Renaissance sundial (Truth in 
reporting -- dial was adjusted to read more accurately than typical).
-12 second video of Sundial Cannon firing.
-4 second video of Kate Pond's Odyssey of Light sculpture performing 
near the fall equinox.
-10 second video of Kinex toy gizmo used to photograph the time-lapse 
for the Odyssey of Light video.

Amateur video editing and effects were done with Adobe Premier 
Elements.  I have only used a few video editing programs, and this was 
the most versatile, and not terribly hard to learn.

-Bill

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Re: Info on a new sundial

[Bill Gottesman]

It looks like it may have been a freebie (langiappe) given at a French
sundial society meeting.

Fun
sundial! This is a model of what was a fairly common type of
portable sundial about 200 years ago, but I don't recall the name.
Suspend the dial from a string tied around the elongated slot and
centered over the current month . There is supposed to be a tiny wire
or thin rod, or some other protrusion protruding a little bit from nose
of the engraved sun. Hold the string, and turn the dial so that the
protrusion casts a long shadow, and read the time from where the shadow
crosses the current month line.
  
-Bill G.
  
Rixx wrote:
  

  

  Hello People! 
I just got a strange little sundial, its a coin, elliptical, about 1"
by 1 3/8", apparently made of sterling silver. 
  
There is a hole through the coin at the sun marker, I assume for some
sort of gnomon to be inserted.
  
Across the top seems to be the months, and on the back it looks like a
map of Europe with some city markings.
  
  http://www.yellott.com/sun/sun1.JPG
  
  http://www.yellott.com/sun/sun2.JPG
  
I'd
like to know how to use it, anyone know? I know being so small it will
not be very accurate, especially since I am in the states (approx 31
degrees).
Any help appreciated,
Thanks!
Phil Yellott
  
  

  


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Re: Off topic but I thinkyou'll enjoy this.

[Bill Gottesman]

Hi Tony,

My wife and I were Susan-Struck about 2 days ago.  We have watched it so 
many times that of the 20 million You-Tube hits, my wife and I are 
probably responsible for about 2 million of them.

If you are British, then you must be able to sing like that too.  I 
think you owe a performance at the next NASS event you attend.

-Bill

Tony Moss wrote:
 Fellow shadowWatchers.
  The following link has nothing 
 whatsover to do with sundials but it would be a sin not to share it.  
 Apologies if you've already seen it.

 http://www.youtube.com/watch?v=9lp0IWv8QZY

 Tony Moss.
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Re: Translations

[Bill Gottesman]

I, too would like to see the math.  I would love to try and work this
out, but I don't have the time at present, and I'm not sure I am up to
the task anyway.  I can imagine that it may involve an "envelope" of
line intersections, much the same way an astroid is a curve drawn from
intersections of lines strung across a square.  Fred Sawyer wrote a
British Sundial Society article in 1994, using this type of math as
applied to the analemmatic sundial at Longwood Gardens in Pennsylvania.

-Bill

Willy Leenders wrote:
Is there anyone who understand the mathematics behind the
sundial concept, i.e. determining the hour lines so that the curved
form of the shadow touches this lines in a point at the concerned time ?
  
  
  
  
  
  Willy LEENDERS
  Hasselt in Flanders (Belgium)
  
  
  www.wijzerweb.be
  
  
  
  
  
  Op 16-jun-2009, om 12:12 heeft Frans W. Maes het volgende
geschreven:
  
  
Dear Steve and all,


Three free translators I sometimes use
for websites or short texts, are:
- Babelfish: http://babelfish.yahoo.com/
- Google: http://translate.google.com/
- Prompt: http://www.online-translator.com/


You may try each on the AFP press release:
http://www.google.com/hostednews/afp/article/ALeqM5gFPjvks3c5EemskZkRWhCB-Fu_IA
and judge the quality (when you read
French and English) or see whether 
you get the message. In this case, the
photos set the stage for the 
story, so that makes it easier.


For this limited sample, I think Prompt
does a slightly better job than 
Google, and Babelfish is last. What do
you think, Joël?
Prompt marks the words that were not
translated, such as proper names, 
which is handy.


More generally, a simple original, both
in terminology and in grammar, 
leads to a better translation. That's why
e-mail messages often 
translate badly.


For me, the most important paragraph in
this text is how the sundial 
should function:


"Innovation de ce cadran: c'est l'ombre
même du parapet projetée sur la 
voûte du barrage qui permet de lire
l'heure solaire.
Chaque heure est matérialisée par une
"ligne horaire" confectionnée avec 
des plaques en lave émaillée: ocres pour
les heures du matin, vertes 
pour celles de l'après-midi. L'heure
solaire est connue lorsque l'ombre 
tangente l'une de ces lignes."


which translates into:


Babelfish:
Innovation of this dial: it is the shade
even parapet projected on the 
vault of the stopping which makes it
possible to read the solar hour.
Each hour is materialized by a “time
line” made with plates in enamelled 
lava: ochres for the hours of the
morning, green for those of the 
afternoon. The solar hour is known when
the tangent shade one of these 
lines.


Google:
Innovation of the dial: the very shadow
of the parapet onto the arch 
dam, which allows you to get the solar
time.
Each hour is marked by a "line timetable"
made with plates in enamelled 
lava: ochers for the morning, green for
those in the afternoon. The 
solar time is known when the shadow
tangent one of these lines.


Prompt:
Innovation of this face: it is the shadow
of the breastwork cast on the 
arch of the dam which allows to read the
solar hour.
Every hour is fulfilled by a "line per
hour" made with plates in 
interspersed lava: ochres for hours,
green for those of afternoon. The 
solar hour is known when tangent shadow
one of these lines.


In the original, the most essential word
of the entire story is 
"tangente", which apparently is used as a
verb: the shadow of the edge 
touches (kisses, osculates) an hour line.
This may be an uncommon usage, 
as all three utilities interpret it as an
adjective and try to make at 
least some sense out of it.


And I wonder what the lava strips are
made of...


Best regards,
Frans Maes






Steve wrote:

  Confrere:
  
  
  I am interested in translating email
and web 
  pages into English.  I use as example the note 
  from Joel about the Castillon Dam.  The link 
  contained in his email is to a web page
in French and so my question.
  
  
  I use Eudora for mail and have receded
to FireFox 
  version 2.00.18.  However, I have tried various 
  translators with several versions
without much success.
  
  
  My question.  Does anyone use a translation 
  program for email and the web, with
success.
  
  
  Thanks
  
  
  Steve
  Yorktown VA
  
  
  
  
  
  
  At 01:13 PM 6/15/2009, robic.joel wrote:
  
Hello Frans and all,
It's the Castillon Dam, see this AFP
article, you will understand easiler
the principle

Re: Fwd: Direct reading time.

[Bill Gottesman]

I like it.  I would like to hear the story of how it was designed and
fabricated.  Is it located at a residence or a public place?

-Bill Gottesman
Burlington, VT

Robert Bargalló wrote:

  
  -- Forwarded message --
From: Robert Bargalló bargallorob...@gmail.com
Date: 2009/9/17
Subject: Direct reading time.
To: Robert Bargalló bargallorob...@gmail.com
  
  
  Hello All,
  When an
inexperienced person examine a well constructed Sundial, often
underestimate the instrument because it is not marking the official
time and having to make some “antipathetic” corrections of the
indicated time. That is the main reason we have built a sundial that
gives civil time accurately, enough to adjust the minute a non solar
clock that it has stopped. In a word, in our quadrant needless resort
to the equation of time or to the local position versus the Meridian
corresponding to the time zone. No arithmetic corrections are needed.
  Descriptively,
the device is a horizontal sundial with a gnomon consisting in thin
thread nylon. The mechanism presents a 48 teeth gear, powered by an
endless screw, which allows the entire clock to rotate some degrees
around an axis parallel to the Earth rotation axis (around the gnomon).
In other words, the mobile set plays like a hypothetical sundial
indicating the exact civil time is elsewhere, in another position but
in the same geographic parallel. As to the accuracy, the quadrant
presents marks of all the minutes from the 5 h 45 a.m. until the 8 h 15
p.m. The single need featuring the device is that one or twice a week
requires adjusts a rotatable knob to indicate the current date. This
disc, of course, acts on the endless screw and, for that reason, on the
rotation.
  Really, the
rotation movement compensates not only the equation of the time, but
also the error caused for the geographic longitude position of the
instrument.
  For the same
method we can use the sundial giving 3 types of time: the local solar
time, the standard time, or the daylight savings.
  Since we
installed it, from November 2006 to date, it has indicated time with an
error that in no case exceeded one minute.
  Happy Dialling!
   
  
  Robert
Bargalló 
  More information at next blog
  
  
  

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Re: Another mechanical sundial

[Bill Gottesman]

Fer,

Does the arm articulate to show declination?  In other words, does the 
arrow point to the sun exactly, or just the meridian line where the sun 
is?  Declination on March 12 is about 3 degrees south, but the arrow 
looks to be pointing fairly deeply into to the southern celestial 
hemisphere, judging from the angle of the gnomon pedestal.

-Bill

fer de vries wrote:
 Friends,

 In front of the railway satation in Amersfoort, The Netherlands, is a 
 mechanical sundial or better, sunpointer.

 You may read about it at my old website:
 http://www.dse.nl/~zonnewijzer/index-fer.htm

 or directly
 http://www.dse.nl/~zonnewijzer/sunpointer.htm

 Best wsihes, Fer.

 Fer J. de Vries

 De Zonnewijzerkring
 http://www.de-zonnewijzerkring.nl
   
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Re: Another Human Gnomon ... Vertical in Bruz (France)

[Bill Gottesman]

Clever and original.  Thank you for sharing it.  It is so interesting
that in 2009, people are still creating new and innovative designs for
something as old as sundials.  There is no reason this design could not
have been conceived 400 years ago, but it wasn't!

-Bill Gottesman

robic.joel wrote:

  
  
  

  Hi John, Patrick, Willy, Fer and all,
   
  Here is the new one I began last
winter:
  http://www.cadrans-solaires.fr/style-humain-bruz.html
  the vertical morning part is
finished now, I will complete later by the horizontal afternoon part
   
  Best wishes
  Joël 
  http://www.cadrans-solaires.fr/
   
  

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Re: Nasa website

[Bill Gottesman]

According to calculations in Meeus' book, 2009 Solstice is on 12/21 at
12:47:50 PM Eastern Standard Time. This is supposed to be within 1
minute of VSOP87 theory.
-Bill Gottesman

PATRICK O'HEARN wrote:

  Hello
All,
  May I recommend to everyone today's (12/20/09) astronomy picture
of the day athttp://apod.nasa.gov/apod/.
Turkish photographers have taken a beautiful analemma which includes a
total eclipse of the sun. I know many list members already visit the
site regularly but, for those that don't, please do.
  One note however, the description says the winter solstice is on
Tuesday, which differs from almost every source I find listing the
solstice as tomorrow (Monday). Oh well, they are only government
astronomers g
  Happy Solstice to all
  Pat O'Hearn
  Anacortes, Wa, USA
  

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Re: zodiac lengths

[Bill Gottesman]

Well done, Frank!
-Bill Gottesman

Frank King wrote:
 Dear Thomas,

 You ask interesting questions and the
 answers depend slightly on just how
 precisely you want the model the way
 the sun goes round the ecliptic.

 QUESTION 1

   ... do [Gemini and Cancer] share
   *exactly* the same region [on a
   sundial] or not?

 I think it is reasonable to DEFINE
 the 12 regions of the Zodiac as being
 bounded at 30-degree intervals of
 solar *longitude*.  So Aries extends
 from 0 to 30 and so on.

 On the ecliptic, these 12 regions are
 distinct and there is no sharing.

 When you look at the corresponding
 intervals of solar *declination*
 you do, as you say, get sharing.

 In your example:

Sign Longitude Declination
   range  range

   Gemini60 to 90 20.15 to 23.44

   Cancer90 to 12023.44 to 20.15

 As you see, Gemini and Cancer share the
 same range of declinations but for Gemini
 the declination is increasing and for
 Cancer is decreasing.

 The answer to your question is YES.

 So far, this theory has nothing to do with
 the *shape* of the Earth's orbit but it does
 assume that the orbit is a plane which is
 isn't exactly.

 [Solar latitude hovers around zero but it
 isn't exactly zero.  A REALLY pedantic
 discussion about whether Gemini and Cancer
 exactly overlap would take a book!]

 You then ask about dates.  That makes the
 story very much more complicated but it
 doesn't stop Gemini and Cancer sharing
 the same region on a sundial.

 QUESTION 2

   Is the starting date May 20 of one in line
   with the end-date July 22 of the other or not?

 You go too fast.  Who says the starting date
 is May 20?  It sometimes is and it sometimes
 isn't.  You have to worry about the leap-year
 cycle and Pope Gregory XIII and his friends.

 At the moment we are living close to the middle
 of an almost 200-year run of pure Julian
 calendar.  There are no omitted leap-years
 between 1904 and 2096 inclusive.  This means
 there is a steady drift in all the dates you
 are interested in.

 The starting *declination* of one IS in line
 with the ending *declination* of the other but
 when you worry about dates everything becomes
 harder.

 The only sensible answer to this second
 question is NO.  It is no because the dates
 change from year to year.  See the answer
 to Question 4, but first...

 QUESTION 3

   The angles of the ecliptic longitude for
   the zodiacs are equally distributed (each 30°),
   [YES that's right] but what about the angles
   in the earth's orbit around the sun (ellipse)?

 I don't quite understand this.  The ecliptic
 longitude is the same as the angle of the Earth's
 orbit round the sun (though you might want to
 change the sign or add 180 degrees).

 The answer is THEY ARE THE SAME.

 QUESTION 4

   And what about the dates?

 They are horrible!  I have already said there is
 a steady drift in the dates but it is worse than
 that because of the precession of the equinoxes.
 The answer is THE DATES ARE A MESS and...

 QUESTION 5

   The lengths (in terms of time) of the zodiacs
   are not equal, but are they constant each year?
   
 The answer is UNFORTUNATELY NO.  It is easy to
 see that they are not constant by thinking about
 this time of year.  We have just entered the
 sign of Capricorn and at this time of year the
 Earth is closest to the sun.

 That's good news because it gets winter over
 quicker.  Capricorn doesn't last long!  Also,
 this explains why the lengths are not constant.

 Unfortunately, there will come a time when we
 are furthest from the sun in winter.  Capricorn
 will take longer and we could find the northern
 hemisphere covered in ice.

 [ There will then be conferences about trying to
 raise the levels of carbon dioxide :-) ]

 QUESTION 6

   Can anybody give me a better reference than
   Wikipedia...

 The best thing you can do is to ask your girlfriend
 to buy you a copy of Astronomical Algorithms by
 Jean Meeus as a Christmas present.  You can then
 write a proper program to model the Earth-Sun
 system.  It took me about 2000 lines of code before
 I was happy with it but it is a very good way of
 answering your questions!

 Best wishes

 Frank


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Re: 3d sundial-model?

[Bill Gottesman]

To model experimental sundials around 2000 I bought an 8 machinist's 
rotary table (controllable to better than 1 minute of a degree).  I set 
up 3 light sources to mimic the solstices and the equinox, and build 
scale models of my dials and observed the shadows as I turned the models 
on the rotary table.  This is a mechanical old-school approach.  Later I 
found many uses for the rotary table when machining parts on my (small) 
milling machine.  If you attend this year's NASS conference August 
12-15, I will show my modest basement workshop on the tour.

-Bill Gottesman

Thomas Steiner wrote:
 Hi all,
 do you model your sundials before creating them in 3d- software like
 sketchup, blender or so?

 It helps if you want to know if anything around casts some shadow onto
 your sundial.
 I tried sketchup, but I am not yet an expert:
 http://picasaweb.google.com/finbref/SonnenuhrBurgauberg#5430320896494713954

 It would be great if you could tell us/me here about your experiences
 (especially I'd be curious for blender)
 Thanks,
 Thomas
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Re: Porter. Hartness. What's the difference?

[Bill Gottesman]

FYI: Bert Willard, curator of the Springfield Telescope Maker's museum
in Springfield, Vermont has indicated that he will bring both that very
same James Hartness dial, and a Russel Porter mystery dial, to the NASS
convention this August in Burlington, Vermont.
-Bill Gottesman

LJ Coletti wrote:

  Richard,

That particular dial was designed by James Hartness (URL below).

http://www.hartnesshouse.com/vermont-museum/hartness-porter-museum.shtml

Luke Coletti


On 5/20/2010 12:31 PM, kool...@dickkoolish.com wrote:
  
  
Here is one of the Porter sundials in Springfield VT.
http://www.dickkoolish.com/rmk_page/RMK_Pictures/S60-07-31-06/IMGP0754.JPG




  Friends,

Is there a conventional name (like  horizontal',  equatorial',  polar' and
so on) for the sundial constructed as shown below?

Am I right thinking that the name of this construction is "Russell
sundial"?
I mean Prof. Russell Porter, the Palomar Mountain Observatory.

Any help, please.

Aleks
www.sundials.ru

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Re: Russell Porter Sundial?

[Bill Gottesman]

I think the dial could be called a Polar dial, but I favor Equatorial,
because the hour marks will be evenly spaced along a cylindrical
surface, typical of many equatorial dials.  How about shaking things up
a bit, and calling it a Polar Equatorial?  Definitely not horizontal.
-Bill Gottesman

Александр Болдырев wrote:

  Friends,

Is there a conventional name (like  horizontal',  equatorial',  polar' and so on) for the sundial constructed as shown below? 

Am I right thinking that the name of this construction is "Russell sundial"? 
I mean Prof. Russell Porter, the Palomar Mountain Observatory. 

Any help, please.

Aleks
www.sundials.ru

  
  
  
  
  

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Re: My New Sundials

[Bill Gottesman]

Thank you for sharing these. I especially like the coloring and layout
of the KOA Campground dial.
-Bill

John Carmichael wrote:

  
  
  

  
  I have made a new 32 stone sundial that will
soon be
installed at Yanney Heritage Park in Kearney Nebraska. I just thought
youd
like to see it because the stone is so odd.
  
  Also, Ive designed a new 32 colored porcelain
wall sundial for a home near Toronto Canada. It is under construction
now.
  
  And a colored 36 x 30 vinyl dial for the KOA
campground in Great Falls Montana. It is under construction now.
  
  You can see them in super high def on my Flickr
photostream
at: http://www.flickr.com/photos/jlcarmichael/
  Or on my website Photos page at: http://www.sundialsculptures.com/gallery/
  
  
  John
  
  John L.
Carmichael
  Sundial
Sculptures
  925 E.
Foothills Dr.
  Tucson
AZ 85718-4716
  USA
  Tel:
520-6961709
  Email: jlcarmich...@comcast.net
  
  
  My Websites:
  (business) Sundial
Sculptures: http://www.sundialsculptures.com
  
  (educational)
  Chinook Trail Sundial: http://advanceassociates.com/Sundials/COSprings/
  (educational)
  Earth  Sky Equatorial
Sundial: http://advanceassociates.com/Sundials/Earth-Sky_Dial/
  
  (educational)
  Gnomons, Styles  Nodi:
  http://www.flickr.com/groups/1207...@n23/
  
  (educational)
  My Painted Wall Sundial:
  http://www.advanceassociates.com/WallDial
  
  (educational)
  Painted Wall Sundials: http://advanceassociates.com/WallDial/PWS_Home.html
  
  (educational)
  Stained Glass Sundials: http://www.stainedglasssundials.com
  
  (educational)
  Sundial Cupolas, Towers
 Chimneys: http://StainedGlassSundials.com/CupolaSundial/index.html
  
  
  
  
  

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Re: Stainless Steel Spheres

[Bill Gottesman]

There have been several articles in the BSS Bulletin and the NASS
compendium about spherical gnomons. In BSS Bulletin 19.1 (March 2007)
Chris Lusby Taylor wrote about how the sphere is a precise gnomon for a
hours-to-sunset and hours-from-sunrise dial, because it is a special
case for the more general cone gnomon. Fabio Savian has created some
wonderful dials along the same principles. In these dial the shadow of
the sphere does all the work, so it makes no difference whether or not
the sphere is reflective.

-Bill Gottesman

Mike Cowham wrote:

  
  
  
  Dear Dialling Friends,
  I have just visited our local gardencentre and they had a large
quantity of 'Gazing Balls' on sale. These are 8" / 20cm diameter
stainless steel spheres with no obvious seams or stalks, andwith a
mirror finish. They MUST be of use to many of you for dialling, for
making globes or for ?
  They are made by Gardman and they were selling two for 9.99,
quite a bargain. 
  If any of you have ideas how these can be used in dialling, I
will be pleased to hear from you.
  If you make something from them, I am sure that we would all
like to hear.
  
  Have fun,
  Mike Cowham.
  
  
  

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NASS 2010: Any Photos of University of Vermont Physics Dept presentation?

[Bill Gottesman]

Hello All,

If anyone has photos of the presentation at the Univerity of Vermont 
Physics Dept from the NASS 2010 bus tour, please send them to me at 
billgottes...@comcast.net (or to Dave Hammond - see email above).  I 
don't think you can send them via this mailing list.  Dave Hammond said 
we were a good group, and he would like to show our visit to his chairman.

-Bill
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Re: A new look at the Equation of Time

[Bill Gottesman]

  
  
Very nice Kevin. Thank you sharing this.
-Bill

On 9/28/2010 9:05 AM, Kevin Karney wrote:
Dear Colleagues
  
You may be interested in the attached chart of the Equation of
Time for 2011. It is of interest for a number of reasons...
- it
is an 'intrinsic' plot - not thefamiliar cartesian, polar or
analemmatic form.
 An
  intrinsic plot has equal increments of the
  independentvariable along the curve of the plot rather than
  along the x-axis.
 This
  allows the curveto be folded - making a very compact form.
  - it
  is much easier to read than a normal plot, because the day
  points are all equally spaced along the curve.
  - it
  looks good !


  
  
  
  
  

  

The use of an intrinsic plot for the equation of time was
  first used in the Bury St Edmunds dial in the 1860s. SeeF.
  Sawyer: The Bury St Edmunds
  Curve,NASS Compendium12(3), p.29(Sept 2005)or John
  Davies: 'More on the Equation of Time on Sundials', BSS Bull
  17(ii), p.75 (June 2005).
This particular 'Flame' form is one of many possible
  compact folded forms that can easily be generated with a
  spreadsheet.
  
  For the number-obsessed, the chart is very precise. Though you
  cannot of course read it on the chart, the values of EoT are
  exact to within afraction of a second, since I have used the
  2011 polynomial algorithms issued to surveyors and
  navigatorsby HM Nautical Almanac Office. Thechart is for
  noon UT. If anyone would like a copy - correct for their own
  time zone and longitude - please let me know. Or if you are
  familiar withExcel, you can download the spreadsheet used to
  draw the curve from http://www.precisedirections.co.uk/Sundials/Index.html.
  The file is called "Almanac 2010_2011.xls". This has all the
  polynomial coefficients for the Sun and navigational stars for
  both 2010 and 2011.You can see a number of other intrinsic
  plots of the EoT at the above website. Click on the
  'Grange-over-Sands Conference' link.


For the really observant, you will notice a tiny additional
  gap between 31 Dec and 1st Jan: that is there because there
  are 365 1/4 days in a year not 365...


The zodiac signs on the chart mark the day starting the
  astronomical constellations when the Sun's longitude are
  passes 30, 60, 90 degrees etc. This may not conform with the
  astrological dates.


Best regards
Kevin




  
  

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Sad news for the Sundial Community

[Bill Gottesman]

  I learned from JD Gard's website for the ATEN sundials that David 
(Gard?), the inventor of the Aten heliochronometer, has died.

I do not know if the company will still sell the sundial.

I own one of the models, and it is a favorite to show guests.  It is 
readable to better than 1 minute.  I did not know Dave, but I certainly 
admired his originality and skill in manufacturing.

It is worth noting that craftsfolk are mortal, and often their art 
disappears with them.  When I see a dial I like and can afford, I 
generally buy it sooner rather than later.  You never know when someone 
will stop making a dial, whether by choice or not.

-Bill
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Mechanically Complex Solar Compass on sale at auction

[Bill Gottesman]

  
  
I saw (on-line) this interesting sun compass for sale by auction
this coming November 20th. I have not seen anything like it. Other
scientific instruments, clocks, sundials for sale at same auction.
I doubt I will bid on it.
-Bill

http://www.skinnerinc.com/asp/fullcatalogue.asp?salelot=2527M363+refno=++874110

Lot 363 
  Brass Solar Compass by W.  L. E. Gurley, Troy, New
  York, the brass instrument with Burt's solar attachment,
  horizontal circle read by opposing verniers, blued steel needle
  and scale calibrated 0-15 in two segments and engraved W.
 L. E. Gurley, Troy, NY, silvered vertical half circle
  arc graduated to 30 minutes with vernier scale and sighting
  mounts, silvered declination and hour calibrated arcs, dual spirit
  levels, graduated sighting vanes and thumb screw leveling tripod
  attachment, ht. 14 in. 
  Estimate $2,000-4,000 

  

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Re: Burt Astronomical Compass (was Mechanically Complex Solar Compass on sale at auction)

[Bill Gottesman]

  
  
Thank you, John. The brochure is many pages long, with much
description to calibration. It sounds like it was a serious
precision instrument in its day. -Bill

On 11/4/2010 9:00 PM, John Pickard wrote:

  
  
  
  Good morning Bill,
  
  The compass is a Burt Astronomical Compass invented by
William Austin Burt in 1855 or thereabouts. 
  
  Burt described its function and use in some detail.
  
  Burt, William A. (1881) A key to the solar compass, and
surveyor's companion; comprising all the rules necessary for use
in the field. Also, description of the linear surveys, and
public land system of the United States; notes on the barometer,
suggestions for an outfit for a survey of four months, etc.,
etc. New York, D. Van Nostrand. 5th edition. (Facsimile reprint
by Carben Surveying Reprints)
  
  There is also some more information in his biography
  
  Burt, John S. 1985 They left their mark. William Austin Burt
and his sons, surveyors of the public domain. Landmark
Enterprises, Rancho Cordova.
  
  
  The "Key to the solar compass" is available as a free
download from Internet Archive (a wonderful source of all sorts
of old books and journals). Different editions are at the
following URLs
  
  http://www.archive.org/details/keytosolarcompas00burtrich
  
  http://www.archive.org/details/akeytosolarcomp00burtgoog
  
  http://www.archive.org/details/akeytosolarcomp01burtgoog
  
  
  
  Cheers, John
  
  John Pickard
john.pick...@bigpond.com
  
  
  In cold, overcast and rainy Sydney. Where has spring gone?
  

  
- Original Message - 
From: Bill Gottesman 
To: Sundial Mailing List

Sent: Thursday, November
  04, 2010 1:04 PM
Subject: Mechanically
  Complex Solar Compass on sale at auction


I saw (on-line) this interesting sun compass for sale by auction
this coming November 20th. I have not seen anything like it.
Other scientific instruments, clocks, sundials for sale at same
auction. I doubt I will bid on it.
-Bill

http://www.skinnerinc.com/asp/fullcatalogue.asp?salelot=2527M363+refno=++874110

Lot 363 
  Brass Solar Compass by W.  L. E. Gurley, Troy, New
  York, the brass instrument with Burt's solar attachment,
  horizontal circle read by opposing verniers, blued steel
  needle and scale calibrated 0-15 in two segments and engraved
  W.  L. E. Gurley, Troy, NY, silvered vertical half
  circle arc graduated to 30 minutes with vernier scale and
  sighting mounts, silvered declination and hour calibrated
  arcs, dual spirit levels, graduated sighting vanes and thumb
  screw leveling tripod attachment, ht. 14 in. 
  Estimate $2,000-4,000 

 
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Re: What can be calculated with a sun dial?

[Bill Gottesman]

  
  
A few extra:
  The stereographic projection, as used by Oughtred, allows
  calculation of the sun's altitude and azimuth at any (day)time on
  any date, and conversely, the calculation for which date and time
  the sun is at a specific azimuth and altitude. The stereographic
  and the orthographic (analemmatic dials) projections allow
  calculation of the time and azimuth of sunrise/sunset on any given
  date. Capuchin altitude dials allow instant calculation of the time of
  sunrise/sunset at any given date (Alessandro Gunella
showed how capuchin dials are derived from an orthographic
projection in the NASS compendium, June 2008). 
  
  Some dials also calculate equal-hours. Islamic dials have a
  Quibla line pointing to Mecca.
And Hendrik
  Hollander's sundial pint glasses tell when to start drinking!
  
I am curious to
  learn in what manner a sundial calculates the earth's
  eccentricity, aphelion and perihelion.
  
  -Bill

On 11/16/2010 4:38 PM, 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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Re: stop the earth: TI 59 PPX; No No Nooooooo!

[Bill Gottesman]

Roger, Roger, Roger,

Say it isn't so.  I had you figured as an HP 65 or HP 67 kind of guy.

-Bill

On 12/11/2010 1:53 PM, Roger Bailey wrote:

Hi Brent,

I found my old TI 59 PPX program to calculate the look up angle. To 
have a look at the math and the program steps go to this personal 
website folder. http://www3.telus.net/public/rtbailey/SML/ . There are 
two pdf files in this folder, 47 kb and 153 kb, too big to attach to 
this letter.


LookUpAmgle1 is three pages with diagrams and the mathematical steps. 
The diagrams help explain the mathematical steps.


LookUpAnglePPX is seven pages and includes the program steps and a 
couple examples. If anyone is really interested and still has a 
functioning TI 59, I will mail the little magnetic strip with the 
program on request.


Although this programmable calculator program was written 30 years 
ago, the math outlined is still valid. This could be rewritten to 
solve for your longitude and reprogrammed for modern use. I expect 
there are many examples available on the web.


Regards,
Roger Bailey
Walking Shadow Designs

--
From: Brent bren...@verizon.net
Sent: Friday, December 10, 2010 6:22 PM
To: Sundial List sund...@rrz.uni-koeln.de
Subject: re: stop the earth


I was playing with satellite look angle calculator today.

http://www.intelsat.com/resources/satellitedata-pas/calc-look-angle.asp

You chose the satellite you want to work with and then plug in your 
latitude and longitude and it will calculate the azimuth and 
elevation for you.


I think the math behind this program would work for my navigation if 
we could run it backwards.
Input the satellite I was looking at, input the azimuth and the 
elevation at the location and then the calculator would return with 
latitude and longitude.


Do you think this would work?

Does anyone know the math behind these calculators?

Thanks again;
brent

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Re: stop the earth: TI 59 PPX; No No Nooooooo!

[Bill Gottesman]

Summer solstice!  You lucky dog.  -Bill

On 12/13/2010 5:35 PM, John Pickard wrote:
Gee, I'm starting to sound like a grumpy old man. It must be the 
upcoming summer solstice. 

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Wonderful NREL Sun Position Calculator, in time for Solstice fun

[Bill Gottesman]

  
  
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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Re: Puzzle Photograph of the Eclipse - A complete guess

[Bill Gottesman]

This is just a conjecture:  I do not think this focused image of the 
eclipsed sun is a pin-hole artifact.  My guess is that it is a focused 
image by the lens, but is a 2nd or 3rd internal lens relfection.  In 
this manner, the image might be reversed, and its brightness greatly 
attenuated, so as to allow the sun appear to be displaced,  properly 
exposed, and in focus.


I don't see why the front surface of the lens would be hot.  My guess 
about the red glow is that it is a completely different internal 
reflection, and that the circular nature of it is defined by the 
circular edge of a lens component.  I think this would be analogous to a 
telescope's or  binocular's exit pupil.


-Bill

On 1/5/2011 2:54 AM, Frank King wrote:

Dear All,

A collegue pointed his iPhone at the
partially-eclipsed sun yesterday morning
and sent me the result:

   http://www.cl.cam.ac.uk/users/fhk1/Eclipse11.jpg

It is clear that the camera wasn't stopped
down anything like enough but why, he asks,
does he get a pin-hole artifact of the
eclipsed sun?

At this stage of the eclipse the crescent
was the other way round from the way it
appears in the artifact.  This is what one
would expect from an image created by a
pin-hole but not when printed and turned
the right way up!

Could this be an image of the reflection
in the water?

I know almost nothing about iPhone camera
technology and cannot give a convincing
explanation of the physics behind this
artifact.

There is also the surrounding elliptical
red background to explain.  Could that be
an image of the hot front surface of the
lens?

Any thoughts?

Frank King
Cambridge, U.K.

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Re: altitude dial

[Bill Gottesman]

  
  
That is a very impressive both mathematically, and as an original
dial.
-Bill

On 1/25/2011 12:01 PM, Fabio Savian wrote:
hi Frank,
  
  two years ago I designed a variant of the shepherd's dial so it
  became universal (for any latitude).
  
  The moving gnomon is curved (the curve is an astroid) and it may
  move up and down and also around the dial.
  
  The gnomon (the tail of the rooster, the crest and the beak are
  decorative) has to be placed in the point where the curve of the
  date (the Sun declination curve) crosses the curve of the
  latitude. The upper shadow of the tail shows the time.
  
  
  ciao Fabio
  
  
  Fabio Savian
  
  fabio.sav...@nonvedolora.it
  
  Paderno Dugnano, Milan, Italy
  
  45 34' 10'' N 9 10' 9'' E
  
  GMT +1 (DST +2)
  

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A 14th century sundial question from France.

[Bill Gottesman]

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 for the other hours of 
the day with a slanted gnomon, and presume that you have software that 
can easily do that.  Would you be willing to play around a bit with the 
above lengths and see if you can determine what gnomon arrangement might 
yield these data?  Perhaps the dial is vertical rather than horizontal?  
In any case, the data are symmetrical, so the gnomon must be in the 
plane of the meridian.


 Knowing that you like puzzles, I thought I'd pass this one on to you.  
If you don't have time for it, don't worry.  This is not the most 
important problem currently facing the history of astronomy!


 Best, Rich
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Re: Moscow sundial?

[Bill Gottesman]

That is Hilarious!  Maybe for nickle it can read your fortune, too!  
-Bill Gottesman


On 3/11/2011 4:56 PM, Willy Leenders wrote:

Maybe this helps: a bathroom weighting scale on a rail along the midline and the 
instruction on the scale, slide the scale until the date and read your weight and 
time
This suggestion is just to initiate a brainstorming session.

Willy Leenders
Hasselt in Flanders (Belgium)

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Re: BSS Bulletin on DVD

[Bill Gottesman]

  
  
Sign me up, John! How do we pay? Can we use paypal?
-Bill G

On 3/11/2011 11:17 AM, JOHN DAVIS wrote:

  

  

  Dear Dialling Colleagues,
  
  The British Sundial Society is pleased to announce
that the full run of BSS Bulletins, from the start of
the Society in 1989 until September 2010 (a total of 75
issues) is now available on a DVD-R.
  
  The cost of the DVD to BSS members is 25 +pp.
It may also be purchased at a cost of 75 by
non-members, though it would be advantageous to join to
get the lower price! Contact BSS Sales (Elspeth Hill at
mem...@ehill80.fsnet.co.uk)
to purchase, or me for any technical enquiry. 
  
  The BSS is grateful to Kevin Karney, assisted by
Elaine Hyde, for the conversion of the 75 issues into
PDF files. 
  
  Regards,
  
  John
  ---

Dr J Davis
Flowton Dials

  

  
  

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Re: Asking for advice, on starting-up a sundial business

[Bill Gottesman]

Hello David,

I make and sell sundials as a business-hobby, not a business per-se, so 
I may not be best suited to answer your question.  I sell about 4 
sundials per year, ranging from $1,800 to $8,000 each.  I also sell 
about 3 consults each year for sundial layouts at about $75 each.  I 
tell my consult-customers that they can download a program and do this 
for free, but I think they don't want to spend the time and would rather 
pay a little money.


I do not actively advertise other than a rudimentary website, because 
frankly I currently have all the business I want; I do this for a 
part-time hobby, not to make a living.


I am very fortunate to have built a good friendship with Kate Pond, a 
local sculptor who likes to make sun-oriented sculpture.  Working with 
someone who has the skills and interest in building things I would never 
attempt on my own has been very satisfying, and has enabled me to 
affiliate my name with some wonderful public and private projects.  I 
encourage you to seek out similar partnerships.  I read the NASS 
compendium and the BSS Bulletins religiously.  They give access to great 
ideas conceptually and aesthetically.  Please ask for permission and 
give proper credit if you use someone else's idea.  I am not qualified 
to advise on copyright and intellectual property, but issues may arise 
in this domain.


Initially, my customers were first degree relatives.  Now my customers 
are universities, private individuals, high-schools, botanical gardens, 
and museums, roughly in that order.  I have done some gratis work for 
one or two townships in advising and laying out a stone circle and an 
analemmatic dial.  I do not know how my customers find me, but I presume 
it is by finding my website on a google search.


I do not consider myself particularly business-savy.  I decided early on 
that I would try to sell a few well-made expensive sundials rather than 
deal with a lower cost / high volume model, as I did not have a knack 
for running the latter.  I also like the challenge of designing and 
building a technical piece that is an unusual addition to the family of 
sundials.


If I had to do this for a real living I am not sure what I would do to 
scale up.  I would probably try to get some free recognition via 
articles in gardening magazines.  I know William Andrewes got fantastic 
recognition for his sundials via an article in Smithsonian Magazine by 
Dava Sobel.


I think my best advice is to make a high quality product, and to educate 
your customers on what to expect from it (local vs civil time, daylight 
saving, etc.).  Artistically, I would hope you can develop your own 
recognizable style.  There is no mistaking a Spectra sundial, a Wenger 
sundial, or one of John Carmichael's carved stone dials, for example.  
Though those are all examples of custom dials, I am sure even if your 
product is a massed produced one, you can still make it look like an 
Andersson dial.


-Bill Gottesman
Precision Sundials LLC

Exactly a month ago, I asked for information or advice on starting a 
sundial

business - but only received one response to this List, and none privately.

I am not attempting to 'copy' any existing items, or designs - preferring to
develop my own, and using some limited market research which I have done.

Based on earlier information from Martina Addiscott in the UK, I am tempted
to concentrate on the Educational Sector - though I can see that Architects
or Landscapers may also be a good source of orders, for their own projects.

I was even thinking about metal-studs, for interactive 'analemmatic' layouts
on wooden garden decking - simple, cheap, plus adding value to properties.


Can anyone recommend the best type of information (and/or products) to sell,
plus where the largest 'customer-base' might be - like schools/gardens, so
that I could begin to think about this.  There are obviously lots of sundial
businesses in the world, and I like the idea of making money from my hobby!

Any appropriate information or suggestions, would be very much appreciated.


My regards to all,

David Andersson.

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Re: Multignomon Sundial

[Bill Gottesman]

  
  
Fabio, these are really wonderful ideas. I would not have
understood your block dial idea if I had not learned about
shadowplane dials fom Mac Oglesby and, I believe, Fer de Vries.
-Bill

On 6/13/2011 8:31 AM, Fabio Savian wrote:

  
  
  
  ... or to get the shadows
  alignment without the hour line
  
  Fabio
  
  Fabio Savian
fabio.sav...@nonvedolora.it
Paderno Dugnano, Milan, Italy
45 34' 10'' N 9 10' 9'' E
GMT +1 (DST +2)
  

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Re: E o T diagram

[Bill Gottesman]

I do not know the answer to this question:

Looking at the intersections of the EoT and Mean Time curves in M. 
Garcia's diagram, is there any reason to conclude that the area of the 
intersections outside the mean time curve must equal the area of the 
intersections inside the mean time curve?  The areas look similar.


My initial hunch is no, but I do not see how to readily prove or 
disprove this.


-Bill

On 6/23/2011 1:27 PM, Miguel A. Garcia wrote:

https://picasaweb.google.com/mgarrando/ECUACIONDETIEMPO?authkey=Gv1sRgCIDLsdzsp52i_AE#5621470247522825746


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Re: Azimuth calculation/Wall declination

[Bill Gottesman]

  
  
About 10 years ago I worked out a simple method to measure wall
declination using just a carpenter's square and an accurate watch. 
The methods is described here http://www.precisionsundials.com/wall%20declination.pdf,
and a simple windows program that does all the calculations for you
is here http://www.precisionsundials.com/walldeclination.exe. 
When I tested it out many years ago, I believe it gave results
repeatable at different times and on different days to a few tenths
of a degree.

-Bill

On 7/31/2011 9:57 AM, Andrew Theokas wrote:

  

  Fellow dialists:
   
  I am using the following well known formula to calculate
the sun’s azimuth for a particular time and location:
   
  Azimuth= tan-1    (sin
  H/(sin φ*cos H – cos φ*tanδ)
   
  where 
  H= Sun’s
hour angle
  φ= the latitude - 42.3 degrees
  δ is the sun’s declination -
  18.62 degrees
   
  The location
is in Boston, USA or 42.3 degrees N and 71.04 degrees west
   
  I am using
the azimuth-azimuth approach to find the declination of a
wall found here:
   
  http://www.mysundial.ca/tsp/wall_declination.html
   
  the time the
measurement was made was 11:18 am (daylight savings time is
in effect)
   
  I can easily
calculate that the azimuth with respect to the wall is 26.8
degrees.
   
  Here is the
problem: using two other independent methods I find that the
wall’s declination is 20 degrees East.
   
  So 26.8
degrees – Sun’s Azimuth should equal about twenty degrees.
   
  But, using
the above equation I cannot get an Azimuth value to work.
One place where I might be in error is the value of the Hour
angle which I compute to be about –16 degrees.
   
  But you can
also find the Hour Angle on line here at http://pveducation.org/pvcdrom/properties-of-sunlight/sun-position-calculator
   
  Where might
I be going wrong?
   
  Many thanks
for a reply!
   
  Andrew
Theokas
   
   

  
  

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Falling Tree

[Bill Gottesman]

I think quantum physicists Neils Bohr and Erwin Schrodinger would say 
there is no sound until it is observed.  But I don't understand this 
stuff all too well.

-Bill

On 8/10/2011 7:26 PM, Donald Christensen wrote:
If a tree falls in the forest where no one can hear it, does it make a 
sound?



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Re: Fwd: Re: Question on a possible sundial.

[Bill Gottesman]

  
  
I agree that it is not likely to be a sundial.  I wonder what
markings are hidden under the flower bowl.  For example, this could
be an anniversary sundial, marking solar noon with a light beam on a
particular date.  Or maybe it is a type of compass aligned with the
celestial pole.  Or maybe a mirror floats in the bowl, and the user
looks down the tube, and their gaze is reflected up towards the pole
star.  It would be nice to know if there are markings under that
flower-pot!
-Bill

On 8/19/2011 3:19 PM, Frans W. Maes wrote:
Hi all,
  
  
  Thanks to the increased attachment size I can post the illustrated
  question of Duncan Meyers to the list, together with my initial
  response. Any additional suggestions regarding the nature of this
  object?
  
  
  Best regards,
  
  Frans Maes
  
  
   Original Message 
  
  Subject: Re: Question on a possible sundial.
  
  Date: Fri, 19 Aug 2011 08:49:21 -0700
  
  From: Duncan Meyers electr0magn...@msn.com
  
  To: f.w.m...@rug.nl
  
  
  Frans,
  
  
  Yes, you are more than welcome to post it to the mailing list and
  see if anyone else knows or has an idea..  My thought when first
  seeing this was that it would allow light into the tube and focus
  the light to a point which would then move along a line and would
  track not only the time but also the date as well. Yes, the tube
  has lenses inside that has a small image when looking through it.
  Kinda like looking through the end of a telescope and you see an
  image but it is really small and far away.
  
  
  I'm part of a solar spectrograph competition to design and build a
  spectrograph and was thinking about using this model as a setup
  design. So the light would pass through the tube and be reflected
  downward into the vertical tube where it would pass through a
  collimeter and then through the grating.
  
  
  But, thank you for your help. I look forward to seeing what your
  members have to say.
  
  
  Best regards,
  
  Duncan Meyers
  
  Connected by MOTOBLUR™ on T-Mobile
  
  
  -Original message-
  
  From: "Frans W. Maes" f.w.m...@rug.nl
  
  To: Duncan Meyers electr0magn...@msn.com
  
  Sent: Fri, Aug 19, 2011 03:14:40 PDT
  
  Subject: Re: Question on a possible sundial.
  
  
  Hello Duncan,
  
  
  It looks sundialish, but I don't think it is. If the tube is
  pointing at Polaris, it could have been part of a pole-style. But
  no ring with hour numbers, parallel to the equator, is present.
  Neither are there numbers on the rim of the flower bowl.
  
  
  In the old days a type of sundial was known as "noon cannon" (see
  attachment for an example). A lens focused the sun's rays on a
  small, loaded cannon at noon, which then fired. So the
  neighbourhood could synchronize their watches and clocks. But then
  it is necessary to adjust the tilt of the lens holder to the sun's
  noon altitude on that day. And I don't see such an adjustment
  here.
  
  
  What else could it have been? Does the tube have lenses at either
  end? Can the tube slide in the tube holder? If it is a monocular,
  one could perhaps observe enlarged flowers with insects on them or
  so. Or if the sun passes the point in the sky at which the tube is
  aiming (which would occur twice a year) a hot spot could set a
  piece of wood, paper or so on fire, or heat a cup of water.
  
  
  That reminds me of a sculpture with a similar function, the 'Solar
  Orbit Transit Station'. See my website, www.fransmaes.nl/sundials
  and choose "Related objects" in the main menu. It is the first
  thumbnail.
  
  
  Does this make any sense? If you like, I could post your question
  to the Sundial Mailing list, a forum of sundialists around the
  world.
  
  
  Best regards,
  
  Frans Maes
  
  
  
  On 17-8-2011 20:20, Duncan Meyers wrote:
  
  

Hi,


I looked through your site and other sites and can't seem to
figure

  
  out what this is. Do you know if it is an exotic sundial that uses
  a
  
  point of light instead of a shadow?
  
  

Duncan Meyers

503-933-6097

  
  
  
  

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Re: Earth rotations

[Bill Gottesman]

  
  
I think it is 366.25 rotations. The orbit around the sun accounts
for one additional axis rotation to the 365.25 day-to-day
rotations. Yes? No?
-Bill G

On 9/30/2011 11:41 AM, Marcelo wrote:
I think it's a little, a very little less than 365,25
  rotations. This "very little", accumulated through the centuries,
  has introduced an error in the seasons, which caused the Pope
  Gregory to correct the calendary in the 16th century. For all I
  know, the "very little" above is something like 3 days each 400
  years. 
  
  2011/9/30 Astrovisuals m...@astrovisuals.com.au

  

  
Heres an easy question:
How many times does the Earth rotate on its axis in
  a year (to the nearest quarter day)?
You can win lots of bets with your friends with the
  right answer!


  


* David
Widdowson, ASTROVISUALS
  

  

  
  
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Re: Bulgarian Sundial Design

[Bill Gottesman]

  
  
I have not seen this design before. I like it and I think the
public will too. I think it would be useful. -Bill

On 11/16/2011 3:46 AM, Mike Cowham wrote:

  
  
  
  Dear Sundial Friends,
  I have been in contact with a man, Boris Kostov,in Bulgaria
whose father has made what he believes to be a unique sundial.
He has tried to contact this mailing list but has so far been
unsuccessful, so has asked me to forward the information. See
attached pictures.
  Basically it is a fairly standard design of dial but the
innovation is to add the Equation of Time to the gnomon so that
when a finger is positioned such that its shadow falls on the
central line of the hour scale, it is pointing at today's figure
for EoT correction.
  He believes that this idea is new and solicits our opinions.
  
  If you have ever seen such a method before or wish to
comment, please contact Boris Kostov,silveriu...@yahoo.com
  
  Thanks in advance.
  Regards,
Mike Cowham.
  
  
  
  
  
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Re: Bulgarian Sundial Design

[Bill Gottesman]

  
  
I meant to add: How to handle the rapid change in EoT around the
solstices will be challenging. -Bill

On 11/16/2011 3:46 AM, Mike Cowham wrote:

  
  
  
  Dear Sundial Friends,
  I have been in contact with a man, Boris Kostov,in Bulgaria
whose father has made what he believes to be a unique sundial.
He has tried to contact this mailing list but has so far been
unsuccessful, so has asked me to forward the information. See
attached pictures.
  Basically it is a fairly standard design of dial but the
innovation is to add the Equation of Time to the gnomon so that
when a finger is positioned such that its shadow falls on the
central line of the hour scale, it is pointing at today's figure
for EoT correction.
  He believes that this idea is new and solicits our opinions.
  
  If you have ever seen such a method before or wish to
comment, please contact Boris Kostov,silveriu...@yahoo.com
  
  Thanks in advance.
  Regards,
Mike Cowham.
  
  
  
  
  
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Re: paper sundial

[Bill Gottesman]

Fabio, these paper dials are wonderful!  What a great treat.  Thank you so
much.  -Bill Gottesman

On Thu, Dec 15, 2011 at 6:09 AM, Fabio nonvedolora 
fabio.sav...@nonvedolora.it wrote:

   Hi all, news from the clouds.

 I’ve a toy for the end of the year.
 I don’t think this is the very last end of the year, like some Maya
 supposed, and this is a great year, it is better than 2012 :-)  (like the
 same Maya didn’t know) so I hope you have fun with this new section of
 Sundial Atlas.

 You can reach ‘paper sundial’, a menu of Gnomolab, directly at this
 address: www.sundialatlas.eu/atlas.php?gnomolab=3
 You will find 4 models, this number is growing and if you have other
 models to propose, I’ll be happy to develop them in Gnomolab.

 The models may be setted for any coordinates and other features, you will
 get a pdf as replay.
 The 3rd model is designed to be applied to glass windows (you may found
 the declination of the windows with Gnomolab). It has a small gnomonic hole
 you can do with a pin or a small nail, moreover this model may be customed
 with a photo (or a logo). I uploaded some sample photos but anyone may
 upload other photos (public or for personal use).

 Have fun, ciao, Fabio

 Fabio Savian
 Paderno Dugnano, Milan, Italy
 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2)

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Re: Christmas Greetings

[Bill Gottesman]

Very nice.  -Bill Gottesman

On Fri, Dec 16, 2011 at 7:57 AM, Kevin Karney ke...@karney.com wrote:

 Dear Fellow Gnonomists

 The comes with greetings from Elizabeth and myself for a very blessed
 Christmas and a wish for the sunniest of days in 2012.

 The attachment is an intrinsic representation of the Equation of Time. An
 intrinsic curve is one in which equal increments of abscissa are found
 along the curve itself (rather than along a fixed axis - as in a
 normal cartesian graph). Plotting a graph in this way allows it to be
 folded - thus making a compact, but easily readable pictogram. You may
 recall Fred Sawyer's paper (NASS Compendium 12 iii) on the Bury St Edmunds
 dial - which inspired this re-design.

 The curve is 'accurate' for noon UTC, but you may like a copy of the graph
 for noon in your particular Time Zone, incorporating the longitude
 correction. If you would like a copy, then e-mail me with….
 1) the name of your town/village
 2) your latitude and longitude in degrees and minutes
 3) the name of your time zone (e.g CET for Central European Time)
 4) your time zone offset in hours (e.g +1 for CET or -8 for PST)
 5) whether you print on A4 paper or US Letter
 The curves take me seconds to generate, if I get the info exactly in this
 format

 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: Sundials in cinema

[Bill Gottesman]

The dial and the trees show two shadows from different light sources.
 Would it give too much away to explain why that is?  -Bill

On Sun, Dec 18, 2011 at 5:36 PM, Darek Oczki dhar...@o2.pl wrote:

 Dear friends

 I've got two news for those interested in sundials in movies.

 1. In the very beginning of the latest movie by Lars von Trier
 (Melancholia) there is a nice scene shoving a close view of a horizontal
 sundial. Screenshot attached. Later it appears in the film several times
 more but only from a distance.

 2. There is an Indian movie comapany Sundial Pictures. They have an
 interesting sundial animation used as their motion logo. Follow the link
 below to watch it:

 http://sundialpictures.in/index.html

 --
 Best regards
 Darek Oczki
 52N 21E
 Warsaw, Poland

 GNOMONIKA.pl
 Sundials in Poland
 http://gnomonika.pl
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Re: How would this sundial work?

[Bill Gottesman]

There is more of a description of that dial at
http://www.diduknow.info/sun/san6.html#.  It is a horizontal dial of which
the gnomon has been broken off.  It is for use during daytime and at night.
 I presume the rotating plate allows adjustment for telling time by the
moon, depending where the moon is in its ~30 day synodic period.
-Bill

On Tue, Feb 14, 2012 at 9:25 AM, J. Tallman jtall...@artisanindustrials.com
 wrote:

 Hello All,

 ** **

 I came across a picture of a sundial this morning that I found to be
 confusing. See the dial picture on the following web page – it has a
 vertical post gnomon and the dial plate looks like it might be designed to
 rotate about the center:

 ** **

 http://www.diduknow.info/sun/san5.html#

 ** **

 Have any of you seen this dial before and do you have any ideas how it
 might work?

 ** **

 ** **

 Best,

 ** **

 Jim Tallman

 www.artisanindustrials.com

 jtall...@artisanindustrials.com

 ** **

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Re: Cray Research 1984 Sun Dial

[Bill Gottesman]

  
  
I own one, from ebay. It is unique in that the numerals are in
binary. There are many chinese characters on the dial face, but I
do not know what they mean. I have photos if any one wants a stab
at deciphering them.
-Bill
On 4/26/2012 2:26 PM, J M wrote:
A friend of mine noticed this sundial on e-bay.
  
   http://www.ebay.com/itm/Cray-Research-1984-Sun-Dial-/300693750335?pt=LH_DefaultDomain_0hash=item4602be823f#ht_500wt_1105
  
  I got a clock or two over the years but never a sundial.
  
  I've never worked for Cray.
  Anyone familiar with this piece of Cray culture?
  
  -cheers
  
  
  
  
  
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Re: Analemmatic in a public place

[Bill Gottesman]

Very nice.  -Bill

On Tue, May 15, 2012 at 4:15 PM, Mac Oglesby ogle...@sover.net wrote:


 Hello friends,

 Last Saturday I repainted the analemmatic sundial I installed a few years
 ago outside the west entrance to my town's Municipal Center. You can see
 the lower parts of the doors in the background. (The cones and tapes were
 removed on Sunday.)

 http://dl.dropbox.com/u/**3688834/**SundialOutsideMunicipalCenter.**pnghttp://dl.dropbox.com/u/3688834/SundialOutsideMunicipalCenter.png

 The Town Manager, the Police Chief, and the Town Highway Department were
 all very cooperative. All of them seemed quite pleased to have a sundial
 where scores of people would walk over it each day. On a nearby post are
 instructions for using the dial, including how to convert this sundial's
 time to clock time.

 For a view of the condition of one of the hour point labels before the
 repainting, look here:

 http://dl.dropbox.com/u/**3688834/HourPointElevenBefore.**pnghttp://dl.dropbox.com/u/3688834/HourPointElevenBefore.png

 The entire process, working alone and including vacuuming the pavement,
 took between 3 and 4 hours.

 I'm hoping that when the next refurbishing comes due there will some
 volunteers to help with the hands and knees part, at least.

 Fondest Regards,

 Mac Oglesby

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Re: Transit of Venus

[Bill Gottesman]

Sara,

1) That is pretty original.
2) It won't be copied by anyone in our lifetime.

-Bill

Ken Launie, proposed to me between first and second contact of Venus on
the Sun as we shared an eyepiece
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Re: New analemmatic

[Bill Gottesman]

What does the writing along the top and bottom of the dial say in english?
 -Bill

On Sat, Jun 16, 2012 at 4:26 AM, Perit Alexei Pace a...@onvol.net wrote:

 Dear all,

 An analemmatic sundial (humbly designed by the undersigned) has now been
 completed in the village of l-Għarb in Gozo (Malta).  We just need to
 indicate the monthly durations of June and December.

 Some images here:

 https://plus.google.com/u/0/114664468598779337464/posts/5hDzAE4eLUV
 https://plus.google.com/u/0/114664468598779337464/posts/TmXYYkxuy7Q
 https://plus.google.com/u/0/114664468598779337464/posts/RCAfvW5sn3X

 Best regards,

 Alexei


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Shadow Clock Kit

[Bill Gottesman]

Hello Sundials Listers,

This is not a sundial, but a kit for a clock that is kinda like a sundial -
it tells time with shadows.  How did we miss this?

http://evilmadscience.com/productsmenu/tinykitlist/156

I ordered mine today.

-Bill
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Re: Shadow Clock Kit

[Bill Gottesman]

I am so ashamed. -Bill

On Wed, Jun 20, 2012 at 5:17 PM, Fred Sawyer fwsaw...@gmail.com wrote:

 Bill

 You need to read The Compendium more closely!  This kit was mentioned on
 p.40 in last September's issue.

 Fred


 On Wed, Jun 20, 2012 at 5:02 PM, Bill Gottesman billgottes...@comcast.net
  wrote:

 Hello Sundials Listers,

 This is not a sundial, but a kit for a clock that is kinda like a sundial
 - it tells time with shadows.  How did we miss this?

 http://evilmadscience.com/productsmenu/tinykitlist/156

 I ordered mine today.

 -Bill

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Re: The most exact sundial of the world In Samedan!

[Bill Gottesman]

  
  
Hello All,

I am a little confused: Who made this dial?
I think it is magnificent. The setting is stunning, the rock
mounting is dramatic. This is a first-class project.

I would be interested in reading (in English) how it was mounted,
how it was aligned, how it was engraved, how the discs are
mechanically assembled and what kind of bearings are used to
minimize play. I hope an article in the NASS Compendium, or the BSS
Journal is forthcoming.

Although the Renaissance double focusing dial can be read to
within 10 seconds, in practice it has mostly only been accurate
to within 1 minute, and sometimes worse. This is because the
Equation-of time is an average over the current 4 year cycle, and is
further due to imperfections in the roundness and concentricity of
the helix and imperfections in polar alignment. 

-Bill Gottesman

On 6/25/2012 3:55 PM, Frans W. Maes
  wrote:

Dear
  Fabio, Roger  all,
  
  
  It is always interesting and instructive to consider claims of
  extraordinary properties; in this case, a temporal accuracy of 10
  seconds. The final accuracy of a sundial is the result of several
  factors, among which the accuracy of orientation and mounting.
  
  
  However, the basic factor here is the accuracy with which a hair
  line can be placed in the exact center of a strip of light by
  rotating a disk. The attached photo nr. 7 from the following pdf,
  taken from Fabio's site:
  
  http://www.sundialatlas.eu/photo/CH/156/CH000220_2_A.pdf
  
  sets the stage. The slit (the gnomon) is placed at the center of
  rotation of the disk that carries the hair line.
  
  
  Ten seconds of time corresponds to a rotation of 2.5 minutes of
  arc around the polar axis. So the question is: can the hair line
  be placed on the theoretical center line of the light strip with
  an accuracy of 2.5 arcminutes? I think that only actual
  experiments can answer this question, but I am doubtful.
  
  
  The edges of the light strip are sharpest close to the gnomon, but
  the lateral displacement of the hair line due to rotation is small
  there. Further out (to the right in Fig. 7) the light strip gets
  wider, with fuzzier edges. What would be the best distance from
  the gnomon to look for estimating the center? And what accuracy
  would be feasible? Does anyone know about experimental data on
  such a task?
  
  
  As far as I know, the only case where a reading accuracy of 10
  seconds of time is achieved, is in the double focusing sundial of
  Bill Gottesman; see:
  
  http://www.precisionsundials.com/sundial_list.htm (scroll all the
  way down).
  
  
  Best regards,
  
  Frans Maes
  
  
  On 24-6-2012 20:09, Fabio nonvedolora wrote:
  
  On Sundial Atlas there is the card of this
sundial with 4 pdf files

  
  attached, one of them with technical info. All of them are in
  german.
  
  www.sundialatlas.eu/atlas.php?so=CH220


ciao Fabio


Fabio Savian

fabio.sav...@nonvedolora.it

Paderno Dugnano, Milano, Italy

45 34' 10'' N, 9 10' 9'' E, GMT+1 (DST +2)


From: Reinhold Kriegler

Sent: Sunday, June 24, 2012 4:39 PM

To: Sundial Mailingliste

Subject: The most exact sundial of the world In Samedan!


Dear friends! Have a look to Switzerland!


Genaueste Sonnenuhr der Welt steht im Engadin

Auf Muottas Muragl auf 2456 Meter ber Meer ist am Donnerstag
die genaueste Sonnenuhr der Welt eingeweiht worden.


 a..
http://www.bote.ch/vermischtes/genaueste-sonnenuhr-der-welt-steht-im-engadin

 Quelle: suedostschweiz.ch

 b.. Datum: 22.06.2012, 17:00 Uhr

 c.. Webcode: 39872


O I love the superlatives in connection with sundials!! :-)


So far this one I did not know: The most exact sundial of the
world!



Best regards


Reinhold Kriegler






* ** ***  * ** ***


Reinhold R. Kriegler


Lat. 53 6' 52,6" Nord; Long. 8 53' 52,3 Ost; 48 m . N.N.

GMT +1 (DST +2) www.ta-dip.de


http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html

http://www.ta-dip.de/salon-der-astronomen/bewohner-des-salons-der-astronomen

Re: Sundial found in Jamestown excavation

[Bill Gottesman]

  
  
Fred's rediscovered Serle's dialing scale plays an important role in
this video. Fred, did the archeologists contact NASS for advice,
and did the scale come from you? The person demonstrating the scale
could have been a bit more careful to make sure the drawn dial lines
all intersected at the origin of the string-hole, but otherwise, the
scales did the trick!

-Bill

On 6/27/2012 1:07 PM, Fred Sawyer
  wrote:

An exciting find in the Jamestown excavation - a 17th
  century diptych dial.
  
  See the article at: 
  
  http://popular-archaeology.com/issue/june-2012/article/archaeologists-unearth-rare-17th-century-find-at-jamestown-excavations
  
  Be sure to view the video that shows the actual uncovering of the
  dial and the reverse engineering that determined the latitude for
  which it was made. Note that the dialing scale the archeologist
  is using is a NASS scale I provided to members many years ago at
  the first NASS conference. (BTW if you haven't yet sent in your
  registration for this year's conference in Asheville NC, please do
  it soon!) I believe the instructions he was using came from the
  Compendium article by Steve Woodbury.
  
  Fred Sawyer
  
  
  
  
  
  
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DeltaCad on a mac

[Bill Gottesman]

Hello Listers,

The delta cad website now says DeltaCad will run on the Mac operating
system.  Has anyone tried it out?

-Bill
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Re: St. Margareth

[Bill Gottesman]

Thank you for sharing this dial.  It is a great example of the quiet
strength of simple design elements.  The blue background with white lines
and numbers is friendly to the eye and eye-catching at the same time.  The
symmetry of the annular dials surrounding the round stain glass windows is
very satisfying.  Bravo to the designer for keeping it understated and
without furniture.
-Bill

On Wed, Aug 1, 2012 at 4:39 AM, Reinhold Kriegler
reinhold.krieg...@gmx.dewrote:

 **

 Dear friends,

 ** **

 did you see already the “sundial of the month *August”* at Joël 
 Robic’ssplendid website on b
 **eh**alf of the Olympic Games…

 http://www.cadrans-solaires.fr/cadrans-Londres-saint-margareth.html 




 Regards,

 Reinhold Kriegler

 **
 **

 ** ** ***  * ** 

 *Reinhold R. Kriegler*

 *Lat. 53° 6' 52,6 Nord; Long. 8° 53' 52,3 
 Osthttp://www.ta-dip.de/sonnenuhren/meine-sonnenuhren.html
 **; 48 m ü. N.N. **
 *GMT +1 (DST +2)  *www.ta-dip.de*

 *http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html*http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html
 * *

 http://www.ta-dip.de/salon-der-astronomen/bewohner-des-salons-der-astronomen.html
 

 ** **

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Re: Wall declination

[Bill Gottesman]

Charles, for a simple and effective measure see Wall
Declination.pdfhttp://www.precisionsundials.com/wall%20declination.pdf
  and WallDeclination.exehttp://www.precisionsundials.com/walldeclination.exe.
 I do not know how its accuracy compares to other methods, but it is an
easy method to perform.
-Bill Gottesman

On Sat, Sep 22, 2012 at 7:36 AM, Charles Beck chforens...@gmail.com wrote:

 Hello all,
 My first post here, another sundial enthusiast.
 Doing my first sundial on a declining westerly wall.
 Can you share your tips to measure the wall's declination as accurately as
 possible?
 From a sat image I measured 10 degrees tilt.
 With the nail and board method I got 9.2 degrees as an average of a
 morning and afternoon measurement.
 Can I get more accurate?
 regards

 Ch.


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Re: Hurray of Oz !

[Bill Gottesman]

That is incredible Fabio.  How did you figure this out?

-Bill

On Wed, Jan 23, 2013 at 10:07 AM, Fabio nonvedolora 
fabio.sav...@nonvedolora.it wrote:

   Hi Kevin,

 the name is just right, I think to know what it was connected to:
 http://youtu.be/cwofR3J0Gh4

 ciao Fabio

 Fabio Savian
 fabio.sav...@nonvedolora.it
 Paderno Dugnano, Milano, Italy
 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2)

  *From:* Kevin Karney kar...@me.com
 *Sent:* Wednesday, January 23, 2013 1:50 PM
 *To:* Sundial list Sundial list sundial@uni-koeln.de
 *Subject:* Hurray of Oz !

 A rare engine from Australia circa 1930 2hp Sundial type B engine ….
 Best wishes
 Kevin

  --
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Re: NASS Conference

[Bill Gottesman]

Yay!.  -Bill

On Wed, Jan 23, 2013 at 2:23 PM, Fred Sawyer fwsaw...@gmail.com wrote:

 I'm happy to say that the dates and hotel for the NASS conference have
 now been set!

 We will be meeting Aug. 22-25, 2013 in Boston/Cambridge, Massachusetts
 at the Courtyard by Marriott.  Full details are not yet available,
 since I am still finalizing the contract with the hotel (so please
 don't try to make a reservation yet!) - but the dates and location are
 definite.

 In a slight departure from our usual agenda, our 'tour day' on Aug. 23
 will omit the bus ride this year and will focus on two exhibits at
 Harvard - the primary one being the Time exhibit that Sara Schechner
 has mentioned on the Sundial List.  Harvard has the largest collection
 of sundials in North America, and many of them will be on view as part
 of the exhibit.  Sara, who is the curator of the collection, has also
 indicated that we may be able to schedule some special viewings and
 discussion of dials that are not in the exhibit.  Part of the exhibit
 will include walking directions to a few other dials on the Harvard
 campus - and to other Harvard museums with items of interest.  We are
 also looking into the possibility of a visit to the Harvard
 Observatory.

 Details will be available on our website and in The Compendium when
 they become available.  Plan to join us!

 Fred Sawyer
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Re: equation of time sundial

[Bill Gottesman]

Hello All,
I think Mike nailed it, as to what Ken is asking.  I know of no sundial,
other than Mike's here, that directly measures the Eot, rather than somehow
incorporate the EoT calculated elsewhere.  I did not think this was
possible until I saw Mike's solution just now, because a sundial has no way
of measuring Mean Solar Time without a previously calculated EoT chart.  In
Tom Hank's movie Cast Away, he records an analemma on a cave wall, but this
is movie fiction.  His watch was broken and he had no way to measure mean
time, only local solar time.
-Bill

On Sun, Feb 3, 2013 at 5:51 PM, jmikes...@ntlworld.com wrote:

   Ken,

 I think I made a device some time ago to do what you want .

 A cylinder was tilted to the appropriate latitude angle and direction.
 There was a small hole on one side of the cylinder which gave a projected
 a spot of light from the sun on the inner opposite surface where there was
 a graph which showed:
 left to right – the equation of time
 up and down – the sun’s declination.

 The cylinder was driven round using a 24 hour clock motor, so the spot of
 light remained apparently stationary except for changes in the EoT and
 sun’s declination that were read directly from the graph.

 Sadly, I don’t think I have it any more.

 Mike Shaw
 53º 22' North 03º 02' West
 www.wiz.to/sundials


 No virus found in this message.
 Checked by AVG - www.avg.com
 Version: 2013.0.2897 / Virus Database: 2639/6076 - Release Date: 02/02/13

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Re: Sundials of castel parks

[Bill Gottesman]

There is a magnificent public sundial in Australia, seen as a spiral town
square on Google Earth at lat -37.802467, longitude 144.965927 degrees.  It
is flat to the ground, but unlike an analemmatic, it uses the person's
height to tell time, and looks more like a traditional horizontal layout.
 See another photo at http://www.flickr.com/photos/leprecon/97106416/

-Bill


On Tue, Apr 2, 2013 at 2:26 PM, Isabella McFedries 
isabella.mcfedr...@gmail.com wrote:

 In message 
 caf10bvvcvya+c5e5wm82f2fern6n_jogqohagvd6bwdesx0...@mail.gmail.com
   Marton Géza idomes...@mcse.hu wrote:

  Dear All!
 
  I received an invitation to hold a lecture and show sundials of castle
  parks and parks on the world. I ask for your help in this regard where to
  find materials or list about these.
  Regards
 
  Géza Marton
  idomes...@mcse.hu



 There must be hundreds of available pictures, showing sundials used in
 park situations round the world - but in my opinion, the only practical
 ones are Analemmatics (being both 'interactive' and theft-proof).

 However, I am not sure if there are very many of these located at any
 'castles', who usually only have horizontal and wall-mounted versions,
 with maybe an occasional 'armillary sphere' or 'multi-faceted' dial.


 If you think that they might make an interesting addition to your talk,
 I have attached two small photographs - the originals are larger, and
 were taken from the main 'Human Sundial' website at  www.sunclocks.com


 One is a typical park (USA), the other is at a 'castle' (UK) - and I
 hope they will get through the file-size restriction for this List.

 I just wish that Analemmatic sundials were better known - but (if you
 want) there are more pictures of 'park' locations, on that website.

 Sincerely,

 Isabella McFedries.


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Re: A prize for the worst dial of the year?

[Bill Gottesman]

OK, that one is a contender.  -Bill


On Fri, Apr 5, 2013 at 1:21 PM, brianalbinson brianalbin...@shaw.ca wrote:

  Bob

 Try this one.  Solid bronze from the local hardware store.

 Brian

 On 4/4/2013 5:33 PM, Robert Terwilliger wrote:

  Here’s one 

 ** **

 In my neighborhoodhttp://www.twigsdigs.com/sundials/mayfair/mayfair.html
 

 ** **

 ** **

 Bob

 ** **

 ** **

 ** **

 ** **

 ** **

 ** **

 ** **


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Re: person's height sundial

[Bill Gottesman]

Very nice dial.  For it to be a person's height dial, don't you need to
show where people of different heights must stand?  These heights are
marked on the Argyle Square dial in Australia (at least, I think they are).
You have some nice photos on your web site of dials I have never seen
before.

-Bill


On Sun, Apr 7, 2013 at 12:37 PM, Chiu 邱,Chi lian clc...@mx.nthu.edu.twwrote:

 Dear All:

 I'd like to report a person's height sundial in PuLi (埔里), NanTou (南投),
 Taiwan, Rep. of China.
 It's located right at the main entrance of PuTai Senior High School
 (普台高中), N23.9946, E120.9367 and is accomplished in the Spring of 2010 by
 a young lady, Miss Chin-Li Lin (林秦立)，a landscape architect in Taiwan.

 As you see from the attached Google Earth picture, the C shaped broken
 circle has a diameter of about 25 m. The white radiating lines within the
 circle are hour lines made of granite.
 For larger pictures of the sundial please go to
 http://photo.xuite.net/nycl.chiu/1864525/75.jpg first.
 There shows the first picture of a set of eight. Then type c to go to
 the next and x to go backward.

 When one looks at this kind of dial for time, he'd be facing his shadow.
 But the ladies in the last two pictures turned down this idea for then
 their faces would be in shadow. They said: Looking for time in that way,
 being taken pictures in this way.  Ha ha.

 Best,

  ChiLian Chiu
  N25, E121


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Re: Art in dialling

[Bill Gottesman]

Hello Fabio,

Marvelous public sundial!  How did you construct the concrete bowl, and
mark the lines so straight?  I imagine it has a drain for water.

-Bill


On Sun, Apr 7, 2013 at 12:14 PM, f...@solariameridiane.it 
f...@solariameridiane.it wrote:

 Hi all
 this is my work in 2006, created for the city of Borgo San Dalmazzo (CN)
 Italy. The development of the project saw the collaboration of Fabio
 Savian.
 I do not know if it falls between the sundials you are looking for.
 www.sundialatlas.eu/atlas.php?so=IT8328

 Fabio Garnero

 Il giorno 06/apr/13, alle ore 21:12, Mario Arnaldi ha scritto:

 Hi all,

 I am working to an article about the Art in dialling and I would like to
 collect high resolution images of sundial made by artists or also artistic
 sundials. I know that not only Italy is the land of art so I would ask if
 there are some dial made by an artist ouside the Alps, or some artistic
 sundial to include as picture in my article. For example I know the famous
 Dalì sundial, the sundials made by Henry Moore, the dial made by Cocteau.
 There is some other dial of that kind?

 Mario Arnaldi



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Re: Alt Augsburg revisited

[Bill Gottesman]

I will start a guess.  I think the Hour hand below the gnomon was to be set
manually by the user to align with the shadow line from the gnomon.  This
hand was mechanically linked to the central clock dial minute hand, to show
minutes past the hour.  In this manner, a user would use the sundial to get
a close estimate of the exact time, told by an hour hand and a minute hand.
 There exist other less complicated examples of German dials using a minute
hand mechanically linked to some kind of moveable shadow indicator.

The other clock dials seem to show day-of-week and day of month, and maybe
a lunar calendar as well.  Maybe there is an equation of time mechanism as
part of the calendar, but I can not tell.  How these would function, I have
no idea, but I can't imagine that they were mechanically linked to the
sundial.

-Bill


On Fri, Apr 26, 2013 at 8:37 AM, Robert Terwilliger b...@twigsdigs.comwrote:

  I find it curious that nobody chose to respond to, or comment on, the
 instruments illustrated in the book *Kunstuhrmacher in Alt Augsburg* 

 ** **

 I put images online at:

 ** **

 http://www.twigsdigs.com/sundials/kunstuhrmacher/kunstuhrmacher.htm

 ** **

 These instruments had to be expensive, and since there seem to be a few
 surviving, somebody must have purchased and used them.

 ** **

 I have a l lot of questions.

 ** **

  How were these instruments used?

  Were they to be used in sunlight?  If not, what was the gnomon for?

  How and why did the single hand indicate the hours from VI to VI?

   What happened at night?

 Two of them have the sundial-style line and curves to indicate
 declination/astrological sign.

   How did this work?

 ** **

 Is it possible that these instruments were so early that the makers gave
 them the appearance of sundials to give the impression of accuracy to users
 who previously knew only sundials as time keepers?  

 ** **

 The first instrument illustrated is the only horizontal one and it appears
 to have been photographed from the north. It also has a dial (the left one)
 divided into eight segments with engraved illustrations and Latin text I
 wonder what that’s about

  

 Until seeing these photographs I didn’t know such things existed.

 ** **

 Bob

 ** **

 ** **

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Re: Advice please: Good outdoor surface for painting an analemmatic dial

[Bill Gottesman]

I used a paint for concrete on asphalt for an analemmatic about 13 years
ago.  It held up for a few years at least, but then the school repaved the
area.  -Bill G.


On Thu, May 2, 2013 at 3:37 PM, Tom Kreyche tkrey...@well.com wrote:

 Search on Tennis Court Paint and you will get all kinds of interesting
 info...some advertise minimal surface prep and they are non-skid. Most
 appear to be acrylic. I haven't used any but am considering for a
 schoolyard project as wellTom

 --
 *From: *rPauli rpa...@speakeasy.org
 *To: *sundial@uni-koeln.de
 *Sent: *Thursday, May 2, 2013 12:25:24 PM
 *Subject: *Re: Advice please: Good outdoor surface for painting an
 analemmaticdial


 Acrylic concrete adheres nicely, takes coloring well.  But it is toxic as
 it is applied, then dries hard, safe and durable.   Any concrete/plaster
 provider should have good advice about products that adhere to asphalt.  My
 local one is  http://www.sbsg.com/concrete/overview/

 On 5/2/2013 11:55 AM, gerard sheldon wrote:

  re:  Good outdoor surface for painting an analemmatic dial

 I am helping a local school make a human sundial, i.e. an analemmatic
 one, and the school is enthusiastic about the idea.  (My daughter is a
 pupil at that school.)  I have been liaising with the art teacher, and
 the suggestion is that one or more students studying art would mark out
 the layout of the dial on the tarmac/asphalt ground, and then paint on it.
So both a scientific and artistic project.

 The difficulty we face is that the tarmac/asphalt surface is quite grainy
 and not good to paint on.  Do you have any advice on how to get a good
 smooth outdoor surface to paint on (and we want the surface to retain the
 paint) ?

 Any advice would be appreciated.

 Thanks

 Gerard




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Ragtime/Jazz sundial lyric

[Bill Gottesman]

Hello Sundial-Listers,

By happenstance I found a piano roll video performance of Lu-Lu-Lou
(1920's?).  One of the verses ends with:

Lu Lu she's so dumb she'll soon be in the booby hatch
I saw her telling time last night on a sundial with a match.

I don't really recommend the performance, but it is here:
http://youtu.be/o2gscYRU2U4 .  Verse starts at 1:52.

-Bill
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08:09:10 11/12/13

[Bill Gottesman]

Did anyone catch this auspicious moment, 08:09:10 11/12/13?  I missed it,
but will go for another try this PM.

-Bill
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Re: Aussie hours til sunset dial

[Bill Gottesman]

Great Story, Jim.  Mac Oglesby has been a strong proponent of Hours to
Sunset dials for years.  This one is magnificent, thanks for sharing it.
 -Bill


On Tue, Nov 19, 2013 at 4:17 PM, J. Tallman jtall...@artisanindustrials.com
 wrote:

 Hello All,



 I got a link today from a Spectra owner about a really big sundial project
 near him, and I thought some of you might be interested:



 http://hourstosunset.com/



 Here is a pic that shows the aperture nodus:




 http://www.news.uwa.edu.au/201302055408/arts-and-culture/new-shaun-tan-sundial-marks-100-years-uwa



 They have a video available at the first site showing the scale of the
 thing and how the mosaic was installed, in numbered sections. Interesting!





 Best,



 Jim Tallman

 www.spectrasundial.com

 www.artisanindustrials.com

 jtall...@artisanindustrials.com

 513-253-5497



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Re: Calculating the Equation of Time and other Solar Parameters

[Bill Gottesman]

Kevin,

I am excited about your article Basic Astronomy for the Gnomonist.  It
will take some time to digest, but it seems to have a very nice graphic
analysis for the many formulas and solar positioning we deal with.  I
appreciate you making this reference available.

I think what you call a Hectoromos dial is what I have heard described as a
Singleton dial.  Here is a link to a similar (vertical) dial at the
University of Vermont.  Fred Sawyer wrote about the Hectoromos dial in an
early NASS compendium.  I think Plato might have had something to do with
it.

-Bill


On Sun, Feb 23, 2014 at 2:32 PM, Kevin Karney kar...@me.com wrote:

 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
 http://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

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Re: Most accurate Sundial in the World

[Bill Gottesman]

That is pretty bold claim, one which I do not make with my own dials.  This
dial is designed to be readable to 5 seconds, but accuracy could be another
matter.  There are so many variables that affect accuracy, and some are
easily overlooked.  Specifically, critical alignment with the north
celestial pole is extremely hard to achieve.  A magnificently designed dial
can perform only as well as its installation will allow.  Accuracy related
to alignment varies with time of day and the sun's declination;  I have not
done the math for a while, but I think even a misalignment by 1/10th of a
degree an any direction will preclude accuracy of say, 15 seconds for a
least part of the day, during some part of the year.  Year-on-year
variation in the EoT is another matter, but could be properly compensated
if accounted for.

Claims of accuracy (for civil time) can be evaluated only by simultaneous
measurements of dial and clock at different times of day, and different
times of the year.  Even a broken watch is accurate twice a day.

-Bill



On Sun, Apr 13, 2014 at 9:54 AM, cerculdestele . cerculdest...@gmail.comwrote:

 Does anyone know if this record has been broken?


 http://www.engadin.stmoritz.ch/sommer/en/activities/mountain-adventure/mountains/muottas-muragl-mountain-adventures/sundial-muottas-muragl/

 Dan Uza
 Romania

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Re: Sun tracks

[Bill Gottesman]

Here is what I think:
The can is laying on its side with its axis oriented north-south.  A
pinhole is made on the west side of the can (assuming this location is in
the northern hemisphere, and that the zenith of the sun is toward the
south), pointing upward at about 45 degrees.  It captures the sun before it
has reached solar noon, then tracks it all the way to sunset in the west.
 The tracks of the morning sun at the top of the picture appear to
converge; this effect comes from that edge of the film being so close to
can's the pin-hole, where all light rays converge at their origin.  (The
film is wrapped around the inside of the can)

-Bill


On Mon, May 5, 2014 at 8:43 AM, John Foad john.f...@keme.co.uk wrote:

 So . . . what is the explanation?  From the angle of the tracks it looks
 quite far north (or south).  Can the curvature of the soup can do it?  I
 can't see how, whether it was vertical or horizontal.

 John

 -Original Message- From: Thibaud Taudin Chabot
 Sent: Monday, May 05, 2014 10:11 AM
 To: Sundial list
 Subject: Re: Sun tracks


 Do I see a retrograde? (Same azimut, different moments). Where is
 this picture made?
 Thibaud

 At 21:33 4-5-2014, Barry Wainwright wrote:

 The BBC has a series of pictures taken by pinhole camera at
 http://www.bbc.co.uk/news/in-pictures-27221895

 Image 7 is described thus:
 John Rigg: This is a six-month exposure using a pinhole camera made from
 an empty soup tin and photographic paper, not film. The resulting image is
 then scanned and reversed. The trails mark the path of the sun across the
 sky as the seasons change. Days with broken cloud show as a dotted line.

 --
 Barry

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Re: The Bill Gottesman stance

[Bill Gottesman]

I say we tack on as many names as possible.  Roger Bailey told me a few
years ago he reported on this stance independently.  -Bill


On Sat, May 10, 2014 at 3:40 PM, Robert Terwilliger b...@twigsdigs.comwrote:

  I have always been of the opinion that the optimal stance to assume as
 the gnomon of an analamatic sundial is to stand with one’s back to the sun
 with arms raised and palms together thus forming an arrow. What has been
 referred to as “The Gottesman Stance” would certainly be  a significant
 improvement.



 I’m sure my friend Bill will agree with me that hereinafter in the
 literature the combination should be referred to as “The
 Terwilliger/Gottesman Stance”.



 What say you?



 ò¿ó¬

  ~

 Bob











 The Gottesman stance

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Re: Using the moon to find south [SEC=UNOFFICIAL]

[Bill Gottesman]

Thanks, Hank.  Very helpful observations.  The ecliptic north pole lies in
the curve of Draco's (The Serpent) neck.  From your explanation, it seems
that the line connecting the crescents of the moon should always point
approximately to that location, and this should be something easy to test
in the night sky.  Is there a way to use this information (perhaps the time
of year) to help refine finding south by the moon's crescent?  -Bill


On Mon, May 12, 2014 at 3:07 AM, Hank de Wit h.de...@bom.gov.au wrote:

 HI Steve,

 I think I can answer this one approximately. The maths is also beyond me,
 but we can get an intuitive answer without causing too much brain strain.

 The first point to remember is that both the Sun and the Moon travel on
 paths nearly along the Ecliptic. The Sun sits exactly on the Ecliptic, and
 the Moon, deviates plus or minus 5 degrees, because it's orbit is inclined
 by 5 degrees to the Ecliptic. This means that that shadow of the terminator
 between light and dark on the moon must be aligned nearly perpendicular to
 the path of the Ecliptic in the sky - they are in the same plane. So the
 problem reduces to the angle that the path of the Ecliptic makes in the sky.

 To reduce variables even more, let's just think about the Moon when it is
 highest in the sky, along the meridian through South (North in the SH).

 We need a planisphere to visualise, and I found a nice online one here:
 http://drifted.in/planisphere-app/app/index.xhtml

 This planisphere has the Ecliptic marked as a blue line in the sky. If you
 rotate the outer disk to move through the months, and imagine the Moon
 along the Ecliptic and sitting on the north-south meridian you can clearly
 see the tilt of the Ecliptic line, and therefore the line through the horns
 of the Moon if it were located at that point. You can see that this line is
 not directly through north for most of the year, and can be either side.
 The biggest deviations are at the two equinoxes. It is pointing south
 (north) at the solstices. I wonder if the amount of maximum deviation from
 due south (north) is plus and minus 23.5 degrees.

 Many regards
 Hank

 -Original Message-
 From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Steve
 Lelievre
 Sent: Sunday, 11 May 2014 12:22 AM
 To: sundial@uni-koeln.de
 Subject: Using the moon to find south

 Hi folks,

 Only loosely related to my question just posted, I'm interested to know
 more about a primative navigation method I've read of. The idea is that if
 one projects an imaginary line through the cusps of a crescent moon down to
 the horizon, that gives the approximate position of South (or perhaps North
 depending on your hemisphere).

 How accurate is this position compared to true south? I'm guessing it
 depends on the time of year, phase of moon and latitude - can any one
 supply formulae? Working it out from first principles is beyond my math
 ability.

 I'm thinking that if I can use the moon to find south, I can then measure
 the azimuth of the sun and use that to get time of day...

 Thanks,
 Steve





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Re: paperhenge

[Bill Gottesman]

Paper henge is totally awesome.  -Bill


On Wed, Jun 4, 2014 at 7:08 AM, Fabio nonvedolora 
fabio.sav...@nonvedolora.it wrote:

   Hi all

 on sunday there was the ‘Festa delle Meridiane’ (sundial feast) in Aiello,
 a village in the NorthEast of Italy where there are 104 sundials and 2252
 inhabitants.
 There also was a contest to vote for the new 4 sundials (the winner is
 IT11058, Sundial Atlas) and a stand of Orologi Solari (
 www.orologisolari.eu), the italian magazine about gnomonics.

 I prepared for them a paper display that I called paperhenge: it is an A1
 paper sheet (594 x 841 mm or 25.5 x 36.1 in) with a solar compass in the
 middle, outlined for Aiello, and a layout to place 9 paper sundials, on a
 circle, from 120 E to 120 W, every 30°.
 The paper models are the n. 3 of Gnomolab -Sundial Atlas, working with a
 pinhole, printed with different background images, line colours, ecc.
 I draw the layout with Indesign and I got the executive pdf (6.3 MB) for
 digital print. I can easily adapt the layout for other place and event, if
 anyone is interested to paperhenge I’ll be glad to custom it.
 I attach an image, other photos are on Sundial Atlas to describe the
 event.

 The event is in menu ‘gnomonics’  ‘happenings’  choose in the right
 column ‘shows the events of the past’  choose ‘14a Festa delle Meridiane’
 or click here: www.sundialatlas.eu/atlas.php?show=85
 The ‘path’ with all the sundials is ‘le meridiane di Aiello’

 ciao Fabio

 [image: DSCN5931c]

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

[Bill Gottesman]

Well, you could include both ways.  This is a really nice resource you have
provided.  Did you already say the reference for your high precision
calculations?  -Bill


On Thu, Jun 12, 2014 at 1:12 PM, Kevin Karney kar...@me.com wrote:

 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: summer house / sundial

[Bill Gottesman]

Very cute!.  If the room rotated to follow the sun's azimuth daily, the
heart would be present much of the day, and would lengthen towards mid-day.
 -Bill

On Thu, Jan 1, 2015 at 2:00 PM, Willy Leenders willy.leend...@telenet.be
wrote:

 I designed a romantic summer house / sundial and I like to hear your
 comments.

 See:
 http://www.wijzerweb.be/zeshoekprieeltje%28eng%29001A.html


 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








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Re: A question for the mathematically inclined

[Bill Gottesman]

You can download a free excel spreadsheet, sunpositioncalculator at
http://precisionsundials.com/sunpositioncalculator.xls.  The Azimuth page
allows you to input date, latitude, longitude, and azimuth, and it gives
you the civil time, eot, declination, and altitude.  When opening, you must
allow macros to run if the computer asks.

-Bill

On Sat, Jan 31, 2015 at 10:49 AM, Richard B. Langley l...@unb.ca wrote:

 If you know the zenith distance, z, of the sun (90° - elevation angle) as
 well as the azimuth (A) then you could use:

 sin(h) = -sin(z)*sin(A)/cos(delta)

 where delta is the sun's declination. The latitude of the site, phi, is
 not needed.

 Computing the hour angle when the zenith distance is not known is a little
 trickier. In principle, this equation could be used:

 sin(h) = tan(A)*(sin(phi)*cos(h) - cos(phi)*tan(delta))

 but you'll notice that h appears on both sides of the equation. Possibly
 this can be solved in an iterative fashion by selecting an approximate
 trial value for h and using it on the r.h.s. to compute a new value of h.
 You would then use this new value on the r.h.s. and continue the iterative
 procedure until the new value does not change significantly from the
 previous value. I've not actually tried this myself so proceed with caution.

 -- Richard Langley

 On Saturday, January 31, 2015, 31, at 11:05 AM, John Goodman wrote:

  Dear dialists,
 
  Does anyone know a formula for calculating the hour angle given the
 azimuth, declination, and latitude?
 
  I’d like to know the time of day, throughout the year, when the sun will
 be positioned at a particular angle. This will allow me to determine when
 sunshine will stream squarely through a window on any (sunny) day.
 
  I’ve seen several formulae for calculating azimuth. I suspect that one
 of them could be rewritten to solve for the hour angle given the azimuth
 instead of the finding the azimuth using the hour angle (plus the
 declination and latitude). Unfortunately, I don’t have the math skills for
 this conversion.
 
  Thanks for any suggestions.
  ---
  https://lists.uni-koeln.de/mailman/listinfo/sundial
 


 -
 | Richard B. LangleyE-mail: l...@unb.ca
|
 | Geodetic Research Laboratory  Web: http://gge.unb.ca/
|
 | Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
  |
 | University of New Brunswick   Fax:  +1 506 453-4943
  |
 | Fredericton, N.B., Canada  E3B 5A3
   |
 |Fredericton?  Where's that?  See: http://www.fredericton.ca/
|

 -

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Re: Clouding the issue

[Bill Gottesman]

That is an excellent question!  I have seen this photo before, and never
noticed the numbers running twice in a semicircle.  I, too, am perplexed.
I read about this dial in Hester Higton's book Sundials at Greenwich.
 The dial operates on two successive polarizations of light - the first
being when light passes through the selenite strips on the glass, and the
second when light reflects at the the polarizing angle (Brewster's
angle?) off of the inclined dark glass plate behind the front glass.  At
all times of the day the radii will appear of various shades of two
complementary colours.  This is different than how a single piece of
polarized film would be used today.

Does this help anyone figure this out?
-Bill

On Mon, Mar 30, 2015 at 3:48 PM, Maes, F.W. f.w.m...@rug.nl wrote:

 Hi all,

 Wheatstone designed still another type of polarization dial than the one
 described by Jim Mahaffey. A specimen is in the collection of the British
 National Maritime Museum in Greenwich, see
 http://collections.rmg.co.uk/collections/objects/265579.html.
 When viewing the celestial pole, the polarization pattern of the sky is
 visible, consisting of two light and two dark regions, which rotate around
 the pole together with the sun.
 What I don't understand from the NMM dial: why does it have twice the hour
 numbers from 1-12 in a semicircle, while the sun rotates through 24 hours
 in a full circle?
 Allan Mills made a modern version, using sellotape instead of selenite;
 see BSS Bulletin 1998 nr. 1. It has one set of 1-12 hour numbers in a
 semicircle, as one would expect.

 Best regards,
 Frans Maes

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Re: A Digital Sundial on Instructables

[Bill Gottesman]

Brilliant.  First dial I've seen like that. Thanks for sharing
-Bill

On Thu, Apr 23, 2015 at 8:24 AM, Richard B. Langley l...@unb.ca wrote:

 Came across this, this morning:
 http://www.instructables.com/id/Time-oclock-shadow/
 --Richard Langley


 -
 | Richard B. LangleyE-mail: l...@unb.ca
|
 | Geodetic Research Laboratory  Web: http://gge.unb.ca/
|
 | Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
  |
 | University of New Brunswick   Fax:  +1 506 453-4943
  |
 | Fredericton, N.B., Canada  E3B 5A3
   |
 |Fredericton?  Where's that?  See: http://www.fredericton.ca/
|

 -

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


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Re: Die Grieskirchner Kepleruhr

[Bill Gottesman]

Awesome dial.  I have never seen a gapped nodus like that before, not have
I seen the use of mirrors to project an image for when the sun is behind
the wall.  Please tell us who designed this dial, and how it was
commissioned?  I could not find that information in the article.  I work
with mirror gnomons, and am interested in how the installers fine-tuned the
mirror alignment.  Did the mirrors have an adjusting mechanism, and did the
designer have a plan for alignment post-installation?
-Bill

2015-04-13 8:47 GMT-04:00 Josef Pastor j.pas...@gmx.de:

  Liebe Sonnenuhrenfreunde,



 die neue „Sterne und Weltraum“ Heft 5-2015, die ab morgen im gut
 sortierten Zeitschriftenhandel erhältlich sein wird, berichtet auf den
 Seiten 66-72 ausführlich über die „Grieskirchner Kepleruhr“, einer
 vertikalen, ebenen Sonnenuhr.





 Dear Sundialists,



 the German speaking Astromagazine „Sterne und Weltraum“ Vol. 5-2015
 provides an report on the „Grieskirchner Kepleruhr“, which is an vertical,
 plane sundial.





 http://www.spektrum.de/inhaltsverzeichnis/mai-2015/1313010



 Viele Grüße

 Best regards

 Josef Pastor



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Re: NASS site down?

[Bill Gottesman]

Yay!

On Sun, Nov 1, 2015 at 9:53 PM, Jack Aubert <j...@chezaubert.net> wrote:

> Yes, the server died, but has been resurrected with some replacement
> hardware.  It is back up and running now.
>
>
>
> Jack Aubert
>
>
>
> *From:* sundial [mailto:sundial-boun...@uni-koeln.de] *On Behalf Of *Bill
> Gottesman
> *Sent:* Saturday, October 31, 2015 8:07 PM
> *To:* Sundials List <sundial@uni-koeln.de>
> *Subject:* NASS site down?
>
>
>
> Sundials.org is unavailable tonight.  Anyone aware of a problem?
>
>
>
> -Bill Gottesman
>
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Re: 3D digital sundial

[Bill Gottesman]

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
> ---
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>
>
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NASS site down?

[Bill Gottesman]

Sundials.org is unavailable tonight.  Anyone aware of a problem?

-Bill Gottesman
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Re: due east photos

[Bill Gottesman]

Well, if you are going to allow compass directions, then that opens the
door to all loxodromes.  There are an infnite number of loxodromes that
connect two points on a sphere, if you allow loxodrome paths that travel
more than once around the globe!  This gives an infinite number of compass
directions to Mecca.

-Bill

On Thu, Sep 24, 2015 at 4:11 PM, Brent  wrote:

> I think you can face Mecca from 4 directions:
>
> 1. along great circle shortest direction
> 2. along great circle longest direction
> 3. along constant compass method shortest direction
> 4. along constant compass method longest direction
>
> I wonder if it says in Koran to face Mecca in shortest direction?
>
> brent
>
>
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Re: A Happy Leap Year Day to everyone

[Bill Gottesman]

Thank you Frank!  What a fun thing to know!  -Bill

On Wed, Feb 24, 2016 at 3:11 AM, Frank King  wrote:

> Dear All,
>
> As is my four-yearly custom, I wish readers of
> this list a Happy Leap Year Day.
>
> I was delighted, in 2012, when I sent out a
> similar greeting, that not a single reader
> queried why I had sent out the message on
> 24 February.
>
> I will add my four-yearly lament that the
> perfectly good English term "bissextile year"
> seems to be almost obsolete.  Around 100 years
> ago it was in fairly common use.
>
> I continue to applaud the French, the Italians
> and the Portuguese (just to give three examples)
> who still use année bissextile, anno bisestile
> and ano bissexto.
>
> Let us hope that they do not indulge in the
> dumbing-down from which we in the U.K. seem
> to suffer.
>
> Frank King
> Cambridge, U.K.
>
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
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Re: Enquiry relating to the wide polar gnomon and its midnight overlap in polar area

[Bill Gottesman]

Why is the Longyearbyen sundial irrelevant to your project?
- Bill

On Friday, July 22, 2016, Helmut Haase  wrote:

> Hi all,
> When studying the wide polar gnomon one inevitably encounters edge changes
> to be respected. My special focus is on a horizontal dial for a location
> with midnight sun. Around midnight the scale needs two overlapping
> sections. I have designed a solution based on a uniformly convoluted spider
> scale (see attached jpg (203 kB)).
>
> My question: *Is a comparable dial existing anywhere?* My web research
> produced only nil returns. The closest but not relevant hit is the 
> Longyearbyen
> sun dial .
>
> Kind regards
> Helmut Haase
>
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
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Re: Astronomy Picture of the Day (Again)

[Bill Gottesman]

That was awesome, Bob.
-Bill

On Wed, Dec 21, 2016 at 8:43 AM, Robert Terwilliger 
wrote:

> This is a good one!
>
>
>
> Traces of the Sun
>
> http://apod.nasa.gov/apod/ap161221.html
>
>
>
> Bob
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
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Re: Kepler

[Bill Gottesman]

Lord knows how you came up with this.  -Bill

On Fri, Jul 7, 2017 at 5:46 AM, fabio.sav...@nonvedolora.it <
fabio.sav...@nonvedolora.it> wrote:

> Hi, I just finished  a work that has engaged me in the last two weeks.
>
> For those are interested about the Kepler's laws, it
>
> ---
> New Outlook Express and Windows Live Mail replacement - get it here:
> http://www.oeclassic.com/
>
> is an orrery to show the true anomaly starting from the mean anomaly.
>
> The mathematical formula expresses the mean anomaly as a function of the
> eccentric anomaly, function of the true anomaly (the true anomaly is the
> angle of the vector ray that sweeps out equals areas during equal intervals
> of time)
> The problem is that the first formula is not reversible. There are some
> iterative mathematical methods to get the eccentricity anomaly from the
> mean one, with several steps up to the desidered approximation, or it is
> possible the resolution into an infinite series of terms but not a direct
> formula.
>
> Here math limps. But what can not be achieved with a formal language can
> be at hand by changing the language, so suggests Godel.
> So I designed a gear structure to get the mean anomaly from the eccentric
> one, like the formula, ma the movement of the gears, unlike the formula,
> can work contrariwise.
> I attached an image of an orrery, for the moment it is virtual, where
> turning a knob with a costant angular velocity, the mean anomaly, you get
> the movement of a planet on an elliptical orbit, following the Kepler's
> laws.
> The turquoise planet follows the true anomaly and the one outside the
> zodiac follows the mean anomaly.
> This orrery is setted with an eccentricity of 0.7216, far higher than he
> Earth's one (0.0167086), to point out the gear's dinamic and the elliptical
> movement.
> I also upload a video on youtube: https://youtu.be/Y5eSOfd5Imk
>
> This work is the entrance door to calculate the eot with gears instead to
> use the customary cam, this is the target for some future gnomonic projects.
>
> ciao Fabio
>
> Fabio Savian
> fabio.sav...@nonvedolora.it
>
> ---
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>
>
>
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S-Town, John B McLemore

[Bill Gottesman]

Hello Sundial Listers,

I was wondering if anyone of us knew John B Mclemore, the Horologist
protagonist of the This American Life radio show S-Town.  The story
includes his fascination with sundials and astrolabes.  Was he known to any
of us?

-Bill
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