Hi all, Martha had difficulties getting this reply throught to the list and asked me to relay the following: - - - - - - - - - - - - - - - - - - - - - - - - - - -
Thank you John, I am glad you have seen the analemmatic web. Since I began in gnomonics, I thought the better sundial for a place where many people do not pay attention to a sundial, it would be an analemmatic, because it is specially attractive because the human participation required to its functioning. Some time ago it was a discussion on this list about analemmatic sundial next to the tropic as a problem because the shadow length, and I was a little worried about. I wrote Frans Maes and he helped us to determine the better major axis of the dial for this latitude and people height average. We did a small model and we saw the problem is only in certain dates and certain hours and even this, we decided to build it, considering the sundial will work O.K. almost all the year. I went to the sundial the Jun 22 at noon and... guess what... yes, I practically did not have a shadow (an interesting event too), but being at 41° C, I was lonely on the park!! > I noticed that the date divisions are at ten day intervals so > that the correction numbers don't look crowded. If one week > divisions were used, the dateline might get pretty busy. > Looks great the way it is. This has resulted very practical because it is easy to get an average between two values, but in retrospective it would be also necessary to include the date where the correction numbers are, because even if we mention this on the instruction panel, people who try to understand the sundial by themselves, they have problems to identify which date is. I do not know about any analemmatic on the tropics, at least, not in American Continent. Greetings to all, Martha Torreón, Coah., México 25°32' N 103° 27' W ----- Original Message ----- From: "John Carmichael" <[EMAIL PROTECTED]> To: <sundial@rrz.uni-koeln.de> Cc: <[EMAIL PROTECTED]> Sent: Tuesday, February 11, 2003 3:44 AM Subject: Re: Analemmatic sundial in Torreón, Mexico Hi Frans and Martha: That's a fine sundial and a great webpage. I also like the terminator maps, but I particularly like the time correction feature on the date line. This built-in table of correction values solves in a simple neat way the problem of showing the Daylight Savings Time correction (or legal time in Mexico) as well as the correction for The Equation of Time, without the use of a confusing analemma on the date line. I noticed that the date divisions are at ten day intervals so that the correction numbers don't look crowded. If one week divisions were used, the dateline might get pretty busy. Looks great the way it is. I also noticed that this dial is located very close to the Tropic of Cancer, making the dateline almost reach the time line. So this dial is about as close to the Equator as you can make an analemmatic and still have it work ok. There are also problems with analemmatic gnomons being too short in the tropics (Does anybody even know of any analemmatics located in the tropics? I doubt there are any.) John p.s. Is it correct to say that an analemmatic face collapses into a polar dial at the equator? John L. Carmichael Jr. Sundial Sculptures 925 E. Foothills Dr. Tucson Arizona 85718 USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Website: <http://www.sundialsculptures.com> ----- Original Message ----- From: "Frans W. Maes" <[EMAIL PROTECTED]> To: "Sundial List" <sundial@rrz.uni-koeln.de> Cc: "Villegas, Martha" <[EMAIL PROTECTED]> Sent: Monday, February 10, 2003 7:12 AM Subject: Analemmatic sundial in Torreón, Mexico > Hi all, > > An enthousiastic group, headed by Martha Villegas, has established a > beautiful analemmatic sundial in Torreón, Mexico, probably the first one in > the country. > > Read all about it at: http://www.biol.rug.nl/maes/torreon/welcome-e.htm > > A special addition here are the terminator maps, depicting the twilight line > across the Mexican Republic at local sunrise and sunset on three dates. > > Regards, > Frans Maes > 53.1N, 6.5E > > > > - > - -
