December 2019
Page 32

A Sundial Delineated inside a Cone

A technical article detailing the design and mathematics of a sundial delineated inside a right circular cone. Sunlight passing through a polar-oriented slit projects a time-telling strip of light onto the interior surface. An aperture nodus simultaneously projects a spot indicating the solar declination. The article includes formulae for deriving hour lines and the characteristic closed-curve calendar lines.
Dials: Unusual, How Sundials Work, Mathematics of Dialling, Sundial Design & Layout

John Arioni