Sundials - World's Oldest Clocks

# North American Sundial Society

The Land Institute is a not for profit organization based in Salina, Kansas, having a goal to create an agriculture system that mimics natural systems in order to produce ample food and reduce or eliminate the negative impacts of industrial agriculture.  A mile north of the Institue is their Marty Bender Nature Area where Owen Brown has created an art project "Units of Measurement".  According to Jason Beets of the Salina Journal, his project "consists of three sets of sun dials created from praire-colored angled flag poles to symbolically represent the passage of time."

The idea is to meditate on the passage of time.  The first set of three poles, called "In the Beginning" is 1,190 feet east of another set of poles called "The Passage of a Second".  According to the artiist, this is the distance that the earthrotates in one second.  A third site, called "From the Future" is located 723 feet north of "In the Beginning" is placed such that at "... dawn of the summer solstice, the shadows of the sundials at “From the Future” will touch [point to] the sundials at “The Passage of a Second.” Owen said, "I want this installation to make us more aware of where we are, who we are, and how we are ... in relation to the earth, to what we grow, and to what nurtures us."

Interesting art but very poor science.  For each cluster of three flag poles, only the one point to North can work as a sundial.  And the pole needs to be at an angle from the ground equal to the latitude of 38.855° N.  From the photo, the angle is closer to 60°.  Fortunately there are no hour lines on the ground to show the incorrect time of the shadow.

If a dialist computes the distances of separation, again our artist fails.  We need to meditate on using the radius of the earth at Salina, KS, (a value between the earth's equatorial radius of 6378.137 km and polar radius of 6356.752 km. The parallel circumference distance is 2pi*R*cos(lat), which is 27142 km, the distance Salina KS travels in a day.  But what is a day? Here we need to use the sidereal day of 86164.1 seconds (giving one revolution of the earth in inertial space). The distance between "In the Beginning" and "The Passage of a Second" is therefore 27142/86164, resulting in 1,033 ft, not 1,190 ft.  By the way, if we had a telescope and somehow watched the events from one site to another, we would see the event 1 microsecond later.  Another unit of time to contimplate.

The azimuth of sunrise (when the limb of the sun just peaks over the horizon) at summer solstice is a bit messy to calculate, but turns out to be 62.1° measured clockwise from north.  The separation distance between "From the Future" and "In the Beginning" to have the sun's shadow align with "Passage of a Second" is 1,033/tan(62.1), giving only 547 ft, much shorter than the 723 ft designed by the artist.  So for a dialist, there are indeed many things to meditate looking upon and calculating shadows at Owen Brown's "Unit of Measurement" in Kansas.

The heart of the Cosmic Room is an unusual vertical meridian sundial created by sunlight passing through a slot on the roof above.  In winter the solar meridian transit is labeled  with a column of blue tiles and at the spring equinox the tiles change to orange.  The sign "Analemma 12:45" indicates civil time on the spring equinox when the sun is on the local meridian.  With the sun overhead, the beam of light follows the vertical set of tiles downward until it reaches the boundary between orange and blue tiles - the equinox has arrived.  Ruben Nohitol has been photographing this event for the last 16 years, every year since 2002.  From a ceiling hole Ruben marks the image of the sun at 12:45 on the floor with a small green circle.  He does this on dates throughout the year(s), not only creating a nice analemma, but does it with such precision that he is able to notice the slight shifts in solar equinox position through the leap year cycle of four years.

More impressive is the due west sunset on the equinox.   A beam of light streams though a hole in the western wall of his hacienda, across the living room,  through a square hole between rooms, across the Cosmic Room grazing past the vertical sundial and its tiles, and lands as a bright solar disk at the far end of the Cosmic Room on a vertical wood screen mounted on an exit doorway.   To add to the drama of the setting equinox sun, Ruben placed a model of the pyramid of El Cerrito on a shelf in the Cosmic Room blocking some of the sun's rays. The result is a shadow of the the pyramid against the solar disk, giving the illusion of thesun setting over the great pyramid.  You can see his vertical meridian and more at http://www.makeaholeinthewall.com and the sundial in operation at http://www.sundials.org/index.php/dial-links/videos/meridiane See his patience to photograph the real setting sun over the pyramid of El Cerrito in Queretaro, Mexico at http://www.sundials.org/index.php/dial-links/videos/analemmas-time-and-motion

 [photo courtesy of Ruben Nohuitol]

Ruben Nohuitol of Queretaro, Mexico has a unique solarium or “cosmic room” to observe the rays of the sun throughout the year.  He has patiently constructed a wonderful time-lapse video following the sun every day at 12:45 pm.   His construction has a vertical meridiana beam of light descending and then ascending the wall as time passes throughout the year. A second sky-light gnomon creates a classical analemma on the floor.

### Current Sun

Sundial = Civil + EoT

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