Sundial for fabrication and sale of e.g. private sundial, has cusps displaced on plane by following movement of sun in order to read solar time at intersection of clock lines and of locus of cusps displacement

摘要

The sundial has a plane (1) on which a concave mirror is fixed perpendicularly to allow reflected light radiation to a form a caustic with cusps (3). The cusps are displaced on the plane by following the movement of the sun so as to read the solar time at an intersection of clock lines and of a locus of cusps displacement. An inclining system inclines the plane based on a latitude of an observation place and the inclination of the sun.