I incorrectly said that that Chaco Canyon is in Arizona, but it's in New Mexico. That's a great website with good still photos. But you really need to see the time lapse movie to get a real feel for how it works.
John John L. Carmichael Jr. 925 E. Foothills Dr. Tucson Arizona, USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Sundial Sculptures Website: http://www.sundialsculptures.com Stained Glass Sundials Website: http://advanceassociates.com/Sundials/Stained_Glass ----- Original Message ----- From: "John Carmichael" <[EMAIL PROTECTED]> To: <sundial@rrz.uni-koeln.de> Sent: Wednesday, November 26, 2003 6:48 AM Subject: Re: Stab Dial > Hi Edley: > > The most interesting, and only "stab" Dial I've ever heard about is the > famous one at Chaco Canyon in Arizona (That's a neat term for them, or how > about "dagger dial"?) We saw a great video on it at the Tucson NASS > conference. It showed a time lapse movie of the solstice dagger of light > piercing a spiral hieroglyphic drawing on the rocks. The gnomon was two > narrow slabs of natural rock that were vertically stacked with a small space > between. > > To visit it you need to get special permission from the Indians that live > there. > > John > > p.s. Your design is intriguing. Have you thought about maybe making a model > of one? > > > John L. Carmichael Jr. > 925 E. Foothills Dr. > Tucson Arizona, USA > Tel: 520-696-1709 > Email: [EMAIL PROTECTED] > Sundial Sculptures Website: http://www.sundialsculptures.com > Stained Glass Sundials Website: > http://advanceassociates.com/Sundials/Stained_Glass > ----- Original Message ----- > From: "Edley McKnight" <[EMAIL PROTECTED]> > To: <sundial@rrz.uni-koeln.de> > Sent: Wednesday, November 26, 2003 1:30 AM > Subject: Stab Dial > > > > Dear Shadow Watchers, > > > > If anyone is interested in any "stab", "slit" or "groove" dials I'd enjoy > > communicating with them. > > > > Here is a short introduction to a couple of them. > > > > Stab Dials - One > > > > If one were to find, or place a round circular > > column so that it's length pointed toward the north or south > > celestial pole, one could create a sundial as follows: > > > > 1. Place a non-elastic cord around the column, marking where the > > ends crossed. > > 2. Divide the cord into twenty-four equal parts between the > > marks above. > > 3. At some exact hour of sunlight align a blade (of 47 degrees > > width and a half degree sharpness) for minimum shadow width with > > the blade width parallel to the axis of the column, blade > > centerline at right angles to the axis of the column, and sink it > > into the surface sufficient to hold it in place. > > 4. Place the cord around the column, aligning one mark with the > > blade and mark the 24 spots. > > 5. Re-sink the blade into the column at each mark corresponding > > to the hours of sunlight, keeping the blade width aligned up and > > down the column and the point directly toward the center of the > > column. Marking them to show the correct hours. > > > > When the blade is inserted into any of these stab marks it would > > indicate with a minimum shadow the correct hour of the day by > > local solar time, thus being a "shadow plane" dial. > > > > If the blade is lost, or off doing something else somewhere, the > > light reaching to the depth of the stab in the wood would > > indicate the same time. > > > > This is one kind of stab dial. > > > > If one makes the same stabs into other surfaces, maintaining the > > same alignment, it can be seen that they would work as well, even > > if the stabs were scattered about rather than in order. > > > > Since it is difficult to look fully into the stab marks, some > > people widen the marks into grooves roughly a quarter of an inch > > wide or so and find they work well also when fully lit. These > > seem to be commonly called "Groove dials" Others extend the > > blade tip just through a thick shell, putting a colored filter > > over the spot to indicate that certain time. > > > > I've come upon such insights from conversations and thought. If > > there is a body of written material on these dials or related > > ones, I would very much enjoy being informed of them! > > > > Edley McKnight > > > > 43.126N 123.358W > > > > > > > > > > - > > > > > - > -
