Re: Azimuthal dial
Hello Bruno, The style gives a line of shadow. This line intersects the date circles ( or other shaped date lines ) Find the intersectionpoint of the line of shadow and the proper date circle. At that point the time is read. Interpolate between the hourlines if that point isn't just on a hourline. That's all to use such dials. Best, Fer. Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E - Original Message - From: Stucchi <[EMAIL PROTECTED]> To: Sent: Friday, February 25, 2000 3:45 PM Subject: Azimuthal dial > Please, can somebody give a description and usage > of the 'azimuthal dial' that has generated a long > e-mail traffic on this list ? > > Regards, > > Bruno >
Re: Azimuthal dial
Hello Bill, ( and others ) Thanks for your suggestion to use a cord to find the correct intersection point between a date line and the shadow line in an azimuthal dial. Although my program Spin is restricted to latitudes outside the tropics I calculated such a dial for latitude 0 degrees and for suntime. The picture is attached to this mail. It is clear that this dial can't be used during several weeks around the equinoxes. At the equinoxes the time can't be read at all. At that time, half a day the sun is due east and then jumps to due west for the rest of the day. Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E - Original Message - From: Wm. S. Maddux <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Cc: Mac Oglesby <[EMAIL PROTECTED]>; SUNDIAL ; Fer J. de Vries <[EMAIL PROTECTED]> Sent: Friday, January 21, 2000 4:40 PM Subject: Re: Azimuthal dial snip. Fer, please forgive my tampering with your SPIN.GIF, in order to illustrate this suggestion. Bill Attachment converted: Macintosh HD:spin0.gif (TIFF/JVWR) (C6FC)
Re: Azimuthal dial
At 03:01 PM 1/21/00 -0200, Fernando Cabral wrote: > Thank you. As always, I tried to locate this "Mayall and Mayall". The >only thing > "The Sky Observer's Guide : A Handbook for Amateur Astronomers" >by Robert Newton Mayall, Margaret W. Mayall (Illustrator), Jerome Wyckoff >which certainly is not the one you've mentioned. :-( - fernando " It is out of print. Originally published as _Sundials, how to know, use, and make them_, it was last revised and re-published in 1994 by Sky Publishing Company as _Sundials, their construction and use_. It is a pretty good book. You can probably get the 1994 edition (which I think is the most complete) through out-of-print book dealers on the web. --Jim McCulloch
Re: Azimuthal dial
I've got your point. Thank you.
As always, I tried to locate this "Mayall and Mayall". The only thing
I found was "The Sky Observer's Guide : A Handbook for Amateur
Astronomers"
by Robert Newton Mayall, Margaret W. Mayall (Illustrator),
Jerome Wyckoff
which certainly is not the one you've mentioned. :-(
- fernando
"Wm. S. Maddux" wrote:
Beginning on p.180 of "SUNDIALS" by Mayall and Mayall,
there
is a description, and construction advice, for dials of this type.
It includes: ..."However, the shadow will not fall on the outer
arc between 9 in the morning and 3 in the afternoon, unless
the height of the gnomon is proportioned to the altitude of the
sun at noon on June 21. But this makes the gnomon look too
high for the dial. Therefore, the shadow of a shorter gnomon
usually is extended by eye to the date arc during the period
when the shadow the shadow does not fall on the arcs."
I would like to suggest that a string can be loosely tied as a
loop ('bowline") around the base of a "too short" cylindrical
gnomon, and stretched along the center of the gnomon's too
short shadow as in the attached sketch, (SPUN.GIF) in order
to make clear the time as extended to an arc of greater radius
than the shadow. (In sketch, to just before 3 p.m. on 1 April.)
--
Fernando Cabral
Padrao iX Sistemas Abertos
mailto:[EMAIL PROTECTED]
http://www.pix.com.br
Fone Direto: +55 61 329-0206
mailto:[EMAIL PROTECTED]
PABX: +55 61 329-0202
Fax: +55 61 326-3082
15º 45' 04.9" S
47º 49' 58.6" W
19º 37' 57.0" S
45º 17' 13.6" W
Re: Azimuthal dial
Dear Fernando,
>> You don't need a nodus, but just a vertical rod in the center.
>> Read where the shadow of the rod intersects the circle of the proper
>> date.
>> At low latitude this type of dial isn't very useful.
>>
>> Best, Fer.
>Maybe with a very tall rod?
>- fernando
Beginning on p.180 of "SUNDIALS" by Mayall and Mayall, there
is a description, and construction advice, for dials of this type.
It includes: ..."However, the shadow will not fall on the outer
arc between 9 in the morning and 3 in the afternoon, unless
the height of the gnomon is proportioned to the altitude of the
sun at noon on June 21. But this makes the gnomon look too
high for the dial. Therefore, the shadow of a shorter gnomon
usually is extended by eye to the date arc during the period
when the shadow the shadow does not fall on the arcs."
I would like to suggest that a string can be loosely tied as a
loop ('bowline") around the base of a "too short" cylindrical
gnomon, and stretched along the center of the gnomon's too
short shadow as in the attached sketch, (SPUN.GIF) in order
to make clear the time as extended to an arc of greater radius
than the shadow. (In sketch, to just before 3 p.m. on 1 April.)
Fer, please forgive my tampering with your SPIN.GIF, in order
to illustrate this suggestion.
Bill
Attachment converted: Macintosh HD:SPUN.GIF 1 (GIFf/JVWR) (C627)
Re: Azimuthal dial
"fer j. de vries" wrote: Fernando, Another picture of such a dial at Southern latitude 35 degrees and suntime can be seen as followGo to my home page ( URL below ) and use the link "Types zonnewijzers". You find it just above the start of the English part. Beautiful. Now that I've seen one for latitude 52 and another for latitude 35 I started having ideas. What would be the appearence of one for the latitude 0? I can imagine (I don't know if Math and reality supports me) a dial designed as human lips. Imagine a woman puts some lipstick and kisses a piece of white paper. Putting a rod on the center we (I mean, YOU) could perhaps have an Azimuthal dial for the latitude 0? Months Jan, Feb, 1/2 Mar, 1/2 Sept, Oct Nov and December would be represented in the upper lip; the other months in the lower lip. Does this make sense or am I completely stray? - fernando PS - Since I was visiting your site I downloaded your "computation of flat sundials again". I had done once, in the hope that I could write it in C. I don't know what I did to the pages, but I know that in the last few years I have not been able to use a C compiler not even to say "hello world". Perhaps I can program it into my calculator, during a flight. -- Fernando Cabral Padrao iX Sistemas Abertos mailto:[EMAIL PROTECTED] http://www.pix.com.br Fone Direto: +55 61 329-0206 mailto:[EMAIL PROTECTED] PABX: +55 61 329-0202 Fax: +55 61 326-3082 15º 45' 04.9" S 47º 49' 58.6" W 19º 37' 57.0" S 45º 17' 13.6" W
Re: Azimuthal dial
Fernando, Another picture of such a dial at Southern latitude 35 degrees and suntime can be seen as follow Go to my home page ( URL below ) and use the link "Types zonnewijzers". You find it just above the start of the English part. In the Dutch text is a link "andere types". Then you find 2 links to "azimutale zonnewijzers". It is also a good exersice for your Dutch. Fer. Fer J. de Vries[EMAIL PROTECTED]http://www.iae.nl/users/ferdv/Eindhoven, Netherlandslat. 51:30 N long. 5:30 E - Original Message - From: Fernando Cabral Cc: sundial Sent: Thursday, January 20, 2000 10:45 PM Subject: Re: Azimuthal dial What do they say about images and words? I was not paying to much attention to this thread. I thought it was too technical for me. Then I saw this image produced by Fer, and voilá! I understood the whole thing at once. Thanks Fer. - fernando
Re: Azimuthal dial
Wow, this is a very interesting type of sundial! In a sort-of similar manner, would this also work: Instead of a -line- for the gnomon, the reading is taken from a point along the line--perhaps a bead or thicker part of the gnomon, though probably more accurately, even the tip of the gnomon's shadow itself. Then, for each hour the actual figure-8 of the analemma is put right onto the dial plate itself (warped, of course, to account for the type of dial plate). Concentric circles could show exactly the path the bead's (or tip of gnomon's) shadow will follow. So then, when the shadow is low on the dialplate, the reading comes from the bottom of the analemma, and progressively higher as the shadow migrates upwards through the year. Of course, since there is nearly always TWO possible marks for each hour, either the two S-halfs of the figure 8 could be somehow marked as to the time of year, or else two BEADS could be used, and the two S-halves would be placed on separate dial plates--Thus for one half of the year, read from one bead and plate, and for the other half, read from the other. I think it MIGHT work at low latitudes, also, if the bead was suspended above the dial plate. I don't know all the sundialing terms or equations yet, but in my mind this works. If it makes sense to anybody, am i on the right track? Oh yes, one other thing--for a great math tutorial (aside from the one that is provided by one sundial website, somebody mentioned), from Algebra to Trigonometry and more, I have found www.gcse.com to be very good. I've been re-learning forgotten math from their site recently. The only problem with their site is that they use extensive _javascript_ing, so I don't suppose everyone would be able to visit. I am not sure the top level of math taught there, though. Have a great day! ryan weh - Original Message - From: fer j. de vries To: sundial Sent: Thursday, January 20, 2000 11:47 AM Subject: Azimuthal dial Hello Dave,Attached ia an example of such a dial.Spin means spider.The dial is for latitude 52 degrees north, longitude 5 degrees east, timemeridian 15 degrees east ( our wintertime ) ( In summer we use 30 degreeseast as time meridian )You don't need a nodus, but just a vertical rod in the center.Read where the shadow of the rod intersects the circle of the proper date.At low latitude this type of dial isn't very useful.Best, Fer.Fer J. de Vries[EMAIL PROTECTED]http://www.iae.nl/users/ferdv/Eindhoven, Netherlandslat. 51:30 N long. 5:30 E- Original Message -From: Dave Bell <[EMAIL PROTECTED]>To: fer j. de vries <[EMAIL PROTECTED]>Sent: Wednesday, January 19, 2000 9:46 PMSubject: Re: Dali dials> Hello, Fer!>> > In my programs suite zwvlak95 there is a program spin.exe to calculatesuch> > a dial for a horizontal plane with circular scales of date and avertical> > style.> > You also may name this type of dial an azimuthal dial.>> Can you give me a mental (or real!) image of this dial? I had never tried> 'spin' before, and the result is, to say the least, interesting! Is this> basically a flat dial, with a vertical style and nodus? How would one> derive the height from the drawing?>> Thanks!>> Dave>> Fer J. de Vries[EMAIL PROTECTED]http://www.iae.nl/users/ferdv/Eindhoven, Netherlandslat. 51:30 N long. 5:30 E
Re: Azimuthal dial
"fer j. de vries" wrote: At low latitude this type of dial isn't very useful. Maybe with a very tall rod? - fernando -- Fernando Cabral Padrao iX Sistemas Abertos mailto:[EMAIL PROTECTED] http://www.pix.com.br Fone Direto: +55 61 329-0206 mailto:[EMAIL PROTECTED] PABX: +55 61 329-0202 Fax: +55 61 326-3082 15º 45' 04.9" S 47º 49' 58.6" W 19º 37' 57.0" S 45º 17' 13.6" W
Re: Azimuthal dial
What do they say about images and words? I was not paying to much attention to this thread. I thought it was too technical for me. Then I saw this image produced by Fer, and voilá! I understood the whole thing at once. Thanks Fer. - fernando "fer j. de vries" wrote: Hello Dave, Attached ia an example of such a dial. Spin means spider. The dial is for latitude 52 degrees north, longitude 5 degrees east, time meridian 15 degrees east ( our wintertime ) ( In summer we use 30 degrees east as time meridian ) You don't need a nodus, but just a vertical rod in the center. Read where the shadow of the rod intersects the circle of the proper date. At low latitude this type of dial isn't very useful. Best, Fer. Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E - Original Message - From: Dave Bell <[EMAIL PROTECTED]> To: fer j. de vries <[EMAIL PROTECTED]> Sent: Wednesday, January 19, 2000 9:46 PM Subject: Re: Dali dials > Hello, Fer! > > > In my programs suite zwvlak95 there is a program spin.exe to calculate such > > a dial for a horizontal plane with circular scales of date and a vertical > > style. > > You also may name this type of dial an azimuthal dial. > > Can you give me a mental (or real!) image of this dial? I had never tried > 'spin' before, and the result is, to say the least, interesting! Is this > basically a flat dial, with a vertical style and nodus? How would one > derive the height from the drawing? > > Thanks! > > Dave > >Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E -- Fernando Cabral Padrao iX Sistemas Abertos mailto:[EMAIL PROTECTED] http://www.pix.com.br Fone Direto: +55 61 329-0206 mailto:[EMAIL PROTECTED] PABX: +55 61 329-0202 Fax: +55 61 326-3082 15º 45' 04.9" S 47º 49' 58.6" W 19º 37' 57.0" S 45º 17' 13.6" W
