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, approximately 6379 km (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.

Read more at: http://www.salina.com/news/20181027/land-institute-art-project-reflects-on-time-nature

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