Sundial with elevated gnomon support avoiding shadow eclipse
OwnerWilliam J. H. Andrewesinventor
Life of this patent
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Abstract
A hemispheric armillary with arms and supporting a structure for supporting a gnomon over a time indicating dial plate is constructed to avoid the arms' shadows from eclipsing the gnomon shadow on the dial plate.
Claims3
Sundial assembly with an elevated gnomon above a time indicating surface (e.g. dial plate) on support structure having spaced arms above the gnomon with tops exposed to the sun, having substantially parallel sidewalls substantially parallel to sun rays passing between them and of limited thickness, consistent with structural integrity, the apparatus as a whole constructed and arranged so that shadows of the arms on the time indicating surface do not eclipse the gnomon shadow on the time indicating surface due to limitations of the umbra and penumbra of the arm and gnomon shadows on the time indicating surface.
An apparatus for management of gnomon shadowing in relation to a light source comprising a gnomon constructed and arranged between a light source and target surface for projecting a gnomon shadow at the surface at different ratios due to relative movement of the surface, gnomon and/or source, at least one beam structure between the gnomon and source also projecting a shadow on the target surface and the gnomon and beam being so constructed and arranged to prevent total eclipsing of the gnomon shadow by the beam shadow.
Dependencies are inferred from the claim text.