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US 7,114,262 B2Granted
Sundial with standard time display
OwnerWilliam J. H. Andrewesinventor
Life of this patent
Estimating the term…
Abstract
A horizontal sundial (1) that can be used to find standard time accurately and be manufactured on a commercial basis for any specific location, incorporating a gnomonic projection map (1M), a wire gnomon (1a) to indicate the time on a scale (1b), and the point of noon on the map (1c), and a bead (1d) located directly above the center of the dial for indicating the Sun's overhead position on the map (1e), and marking special occasions and special dates.
Claims11
A horizontal sundial apparatus for finding time based on shadow to the nearest minute at a given location comprising:
- (a) means providing a horizontal surface which is reflective and hard but etchable or inscribable and has a gnomonic projection map centered on the location for which it is made and having a time scale and equation of time scale,
- (b) means providing a wire gnomon stretched above the gnomonic projection map between a map-pole position and an elevated position at an angle corresponding to latitude of the sundial's given location to point to the Northern axial point of the Heavens a Northern Hemisphere location or Southern Cross for a location South of the Equator and coordinated with the map to provide a shadow of the wire that indicates noon on the map, and
- (c) a further indicator, formed as a bead along the length of the wire gnomon arranged at the universal point and marking by its shadow on the map, where the sun is directly overhead on a given date.
Dependencies are inferred from the claim text.