J.A.F. de Rijk describes a new, simple, and more accurate latitude-independent sundial, building upon Freeman's 1978 solution. This type of sundial can indicate local apparent solar time without requiring knowledge of the observer's latitude. The article explains the mathematical principles, focusing on how the product sin(Az)cos(h) and sin(T)cos(δ) are obtained and combined to determine the time (T).
Dials: Unusual,
How Sundials Work,
Mathematics of Dialling,
Sundial Design & Layout