Precision Sundials

This site offers double sundials, to tell both solar and time zone time, and a helical sundial which uses special lenses to focus a line of light, instead of a shadow, on the current time. The second is adjustable in two ways, the angle can be set for your lattitude (no need to to custom build to location) and the time markings are on a slider to adjust for daylight savings time and the equation of time.

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