Universal Civil Time Sundial - Spartanburg, South Carolina, U.S.A.
N 34° 57.469 W 081° 55.147
17S E 416084 N 3868750
This unique sundial is located at the back entrance of the Spartanburg County Public Libraries Headquarters.
Waymark Code: WM60K6
Location: South Carolina, United States
Date Posted: 03/12/2009
Views: 9
This sundial consists of two cylinders. One cylinder is for the winter and spring from about December 22 to June 22 and the other is for the summer and fall. Each cylinder has a small ball gnomon to cast the shadow and has indicia for both standard and daylight saving time. Also each cylinder has a grid with the latitude and the longitude displacement of the site from the time zone meridian, and is oriented by use of a watch with the correct time.
Watch time is indicated on the current cylinder by the shadow of the gnomon on the curved mean time lines. Heavy curved lines represent the hours. Lighter curved lines are at ten minute intervals between the hours. The straight longitudinal lines are for time zone sun time.
The approximate date is also indicated by the shadow of the gnomon. The thin circumferential lnes represent the first of months. The upper circumferential line represents the winter solstice about December 22 while the lower circumferential line represents the summer solstice about June 22. The heavy circumferential line midway between the solstices represents the equinox about March 21 or September 23.
The latitude and longitude displacement of the site is indicated by the needle plumb bobs over the site mark on the latitude and longitude displacement grid beneath the gnomon.
The cylinders themselves are tilted up from the horizontal at an angle equal to the latitude of the site and are parallel to the axis of the earth and the axis of the celestial sphere. They are pointing to the celestial north pole where the North Star may be seen at night.
The Universal Civil Sundial with its small ball gnomon to cast a round shadow from all directions and with its civil time indicia correlated with site indicia will be close to watch time. However it can not be precise due to constantly changing Equation of Time values, refraction of the sun's rays in passing through the atmosphere, parallax caused by the distance of the sundial from the center of the earth, and manufacturing and installation tolerances. The shadow on a 6 inch sundial moves only 0.0131 inches per minute.
Sundial Type: Other
Related Web Site: Not listed
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