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
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