This article describes the design and construction of a horizontal sundial with a cylindrical gnomon, which the author calls a "Turnstile Dial." It explains how the shadow is cast from a continuum of tangent points on the rounded gnomon, the practical aspects of its construction using copper, and the plotting of hour lines tangential to a central ellipse.
Construction Projects,
DIY Sundial Projects,
Dials: Horizontal,
Sundial Design & Layout