Hi John, This dial sounds interesting. I'll have to see about getting there some time.
My problem with models, sometimes, like now, is that I've way too many different related dials in my mind at one time, and they are all changing so often as I think about them that I can't settle on the slower process of making a model. I'll write the list about some of the other "stab" dials, if folks are interested. I've used the term "Stab" rather than "Dagger" because some of these dials involve narrow spikes, like an ice-pick rather than a blade. The one I've mentioned here could be called an "equatorial stab dial". Thanks for your interest! Edley. > 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 > > > > > > > > > > > > > > > - > > > > > > > > > - > > > > > - -
