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Armillary Sundial

Equatorial, Universal, Hour angle

Armillary dials are a subclassification of equatorial dials. While armillary dials are not required to possess the design elements of armillary spheres, many do, featuring circles for the tropics and very occasionally the ecliptic, as well as other great circles. These bands may complete full circles, or be cut to allow the dial to be more easily read.


Many simple (and thus unrecognized) armillary dials are commonly referred to as equatorial bowstring dials. This is due to the long gnomon connecting two ends of an arcing support resembling the string of a bow. Many bowstring equatorial dials would readily be considered armillary dials if their cut rings were fully formed.

North American Sundial Society

The Sundial Primer

Overview of Instrument
Use as a Calendar
Outdoor Demonstration
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