Understanding the Equatorial Sundial

This is a simple diagram of the Equatorial Sundial.

The Equatorial Sundial (also called the equinoctial dial), consists of a disc with two faces, each marked in radial lines representing the hours; a gnomon, representing the earth's axis. The dial face is always parallel to the equator, which defines its name. Like all sundials having a fixed gnomon, the Equatorial Sundial also has lines marked at 15 degree interval per hour.

"An equatorial sundial is actually a reduced model of the Earth, similar to a globe with its upper and lower halves removed: the dial plate represents the plane of the Earth's Equator; the gnomon represents the Earth's axis of rotation. The upper dial face represents the Northern Hemisphere; the lower dial face represents the Southern Hemisphere."

(definition derived from "The Sandburg State of Sky Awareness" http://www.wsanford.com/~wsanford/exo/sundials/equatorial_sundials.html)