Hi Mark (&others) How unfortunate that you won't be able to present your paper on the McMath-Pierce Telescope Sundial proposal at the Conference. It's a great idea, especially for the Tucson meeting. I do hope that it gets presented by somebody. Later though, I will be making my own proposal to Kitt Peak for a horizontal version after I've done more research, drawings and measurements. Maybe we could work together on a formal presentation to Kitt Peak? However, I doubt if they would permit hourlines on the vertical Heliostat tower, not only because of temperature and paint concerns, but because the structure is an architectural icon here and painting lines on it might be considered by some to be akin to graffiti. I think a horizontal dial has the best chance of being accepted.
The ground beneath the scope is of asphalt and not perfectly flat and somewhat irregular in shape and is surrounded by a grassy area. If we were to use this surface as is, then the calculations for the hourlines would be very difficult because of the irregular slopes. It would be much easier and more precise to mark the actual shadow lines on a day when the Equation of Time is zero. Hour lines could then be cut into the asphalt and painted. I doubt the cost would exceed $500.00. Or instead of lines, we could use little pile of rocks or vertical cement or metal rods to mark the hour lines. Of course, it would be even better to resurface and extend the area with something nicer than asphalt and use metal inlays instead, but that means money. But who knows? The powers that be just might want to make an investment in the sundial project if we present our case well. The Observatory people I've talked to all seem very interested so far. you wrote: > But there is a minor glitch: The > shadow edge cast by the rather thick, faceted style is formed by the > sloping *top* corner when the Sun's elevation angle is low, and by the > *side* corner when the elevation angle is somewhat greater. This would > frustrate accurate interpolation of hour readings at a particular interval > during mid-morning when the particular edge-in-play switches. That's true. In essence, the gnomon has three styles, two on top and one on the bottom. The same thing would happen in the afternoon, but it could be solved using three sets of hour lines, one for each style. Could you please send your past correspondence with Dr. Pierce if it's not trouble? John 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: "Mark Gingrich" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Friday, May 03, 2002 11:32 PM Subject: Re: Solar Telescope Sundial > John Carmichael wrote: > > > While visiting the mountain of Kitt Peak to prepare for the NASS tour > > visit, I was immediately struck by the similarity between the above-ground > > triangular structure of the McMath-Pierce Solar Telescope and a sundial's > > gnomon.I have been studying the idea of placing timelines of a sundial on > > the ground beneath the giant McMath-Pierce Solar Telescope. ... > > > The McMath-Pierce Solar Telescope's similarity to a dial's style was > recognized even before it was completed. Robert McMath and Keith Pierce > -- for whom the instrument is now named -- mentioned it themselves in an > article that appeared in print just as construction got under way: > > ... the inner telescope was an immense vertical triangle > with its hypotenuse along the polar axis, appearing like > the gnomon or index of a sundial. ... > > [McMath, Robert R. and Pierce, A. Keith. "The Large Solar Telescope at > Kitt Peak." _Sky and Telescope_. August 1960. p. 65.] > > > In 1993 I corresponded with Dr. Pierce to suggest that the structure > could easily be made into one of the largest sundials in the world with > only a few relatively minor additions. But instead of turning it into > a horizontal dial of mammoth proportions, I proposed putting hour lines > on the southeast- and southwest-facing sides of the north, vertical > tower -- a vertical-decliner design that would more easily permit time > readings from afar. (The east and west corners, respectively, of the > sloping tunnel would serve as styles for each facade in this arrangement.) > > Dr. Pierce replied that the telescope-as-sundial idea had been proposed > several times previously, but he was intrigued with the vertical-decliner > idea, though not very enthusiastic about making any modifications to the > tower. The external surface is coated with a special formulation of > titanium-oxide white paint, which is very reflective in both the visible > and infrared portions of the spectrum, necessary to keep the structure > as cool as possible. Non-white hour-line markings thereon, small as they > might be, could only make things worse, temperature-wise. Dr. Pierce > also made the conspicuous point about the telescope's paint job costing > $150,000 (in 1993 dollars). > > The horizontal-dial approach would of course avoid the problem of tinkering > with the functional telescope building. But there is a minor glitch: The > shadow edge cast by the rather thick, faceted style is formed by the > sloping *top* corner when the Sun's elevation angle is low, and by the > *side* corner when the elevation angle is somewhat greater. This would > frustrate accurate interpolation of hour readings at a particular interval > during mid-morning when the particular edge-in-play switches. > > When I learned that Kitt Peak was to be on the NASS 2002 bus tour, I planned > to present a paper in Tucson on this very same idea, tentatively titled: > "A Dialist's Graffito: Remaking the McMath-Pierce Solar Telescope as a > Sundial." But at the moment, job responsibilities may sabotage my chance > to travel. I'm now trying to talk Carl Trost into presenting this paper > in my stead. > > John, if my correspondence with Dr. Pierce has any value to you, to see > exactly what had been proposed in the past, and to learn of Pierce's > reaction, I'll be happy to mail them it to you. No doubt Pierce himself > will tell you about a few letters he's received from a few whacky, > impractical dialists! ;-) > > Oh, and if you can get your hands on the following issue of _S&T_: > > McMath, Robert R. and Pierce, A. Keith. "The Large Solar > Telescope at Kitt Peak -- II ." _Sky and Telescope_. > September 1960. pp. 132-135. > > which is the second installment of the article I quoted earlier, you'll > find some scaled engineering drawings of the telescope (though they seem > to lack explicit dimensions of various features, unfortunately). > > > ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ > Mark Gingrich [EMAIL PROTECTED] San Leandro, California > > - -
