Calendar sundial which indicates the ecliptic plane

摘要

A sundial has a horizontal base 1, a lower wedge 2 mounted on the base, the inclination 12 of which may be adjusted for use at various latitudes, and an upper wedge 4 representing the ecliptic plane rotatably mounted 14 on the upper surface of the lower wedge. The ecliptic plane is inclined at an angle of 23.5 degrees to the upper surface of the lower wedge, the upper wedge being capable of rotation around an axis 14 which is perpendicular to the upper surface of the lower wedge. A dial plate 6 is mounted on the upper surface of the upper wedge. A sighting device 8 has a pinhole 7 which projects a sun beam onto a cross-hairs target 17 when it is correctly aligned by rotating the upper wedge and a pointer plate11 independently. A pointer line 18 permits reading of dates on the dial plate. Time is indicated on the hour scale 3 by use of a pointer line and transfer lines 5. A compass and means to ensure that the base is level may be provided. The zodiac may be displayed on the dial.