Building on Peter Drinkwater's work, this article explores adapting a spherical sundial to indicate mean time for six months of the year, by offsetting the hour marks away from the equator. This is possible because the slanting terminator at different solar declinations, adjusted for corresponding equation of time, happen to fall very close to one of two circles (within 1.5 minutes). The author also discusses using surface texture, like paint brush marks, to significantly improve the dial's readability and precision.
DIY Sundial Projects,
Dials: Unusual,
Equation of Time,
Sundial Design & Layout