Geometrical instruments – Straight-line light ray type – Celestial
Patent
1978-06-15
1981-03-17
Stephan, Steven L.
Geometrical instruments
Straight-line light ray type
Celestial
G04B 4900
Patent
active
042558646
ABSTRACT:
A solar time indicating device in the form of an elongated box-like structure having a slot in one of its side faces for passing sunlight. A light image or line formed by the illuminated slot falls on a translucent side face, containing a proportionately expanded linear time index, disposed opposite the slotted face. The position of the leading edge of the light image along the time index or scale indicates solar time when the parallel, slotted and scale faces are tilted at the angle of latitude and the long axis of the box is disposed perpendicular to the earth's "true" north/south axis. An appropriate support for the tilted box may also include a mirror disposed beneath the scale face to permit easy viewing of the illuminated scale. An alternative embodiment comprises disposing the translucent scale face at the center of the box perpendicular to the slotted face and with the outer opposite parallel faces omitted to permit viewing of the illuminated scale face which is marked with a radial time index. This box may be adjustably mounted upon a suitable support to permit its proper orientation with regard to latitude and with an appropriate shade to overcome problems caused by seasonal variations in the position of the sun. A further embodiment combines features of the other embodiments.
REFERENCES:
patent: 783245 (1905-02-01), Clarke
patent: 825319 (1906-07-01), Hewitt
patent: 933556 (1909-09-01), Hansen
patent: 2207195 (1940-07-01), Guadet
patent: 2536328 (1951-01-01), Triplett
patent: 3486234 (1969-12-01), Waterman
patent: 3786570 (1974-01-01), Daries
Advertising Sheet from Heritage Workshop for "Sun Clock", fall, 1977.
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