Abstract: A sundial with a concave hemispherical body and top surface generally horizontal has longitude displacement, latitude, sun declination, and time indicia originating at the spherical gnomon located at the spherical center of the hemisphere. Site set up is accomplished by plumbing the gnomon over the site latitude and longitude displacement indicia and then rotating on a horizontal surface until the correct time is indicated by the shadow of the gnomon from the sun. Two six-month sundials or two removably attachable inserts are used for indication of watch time for complete years.

Abstract: A typical plate and gnomon sundial with an enlarged dial plate and an extended gnomon is provided with latitude and longitude displacement indicia lines on the dial plate, beneath the gnomon and beyond the time indicia. A point is established on the gnomon from which a plumb line to the latitude and longitude displacement indicia lines can be determined. The latitude and longitude displacement indicia lines are placed so that when a plumb line from the point on the gnomon intersects the point of intersection of the site latitude indicium line with the site longitude displacement indicium line, the gnomon will be inclined to the horizontal at an angle equal to the latitude of the site and the plane(s) containing the gnomon and the 12 o'clock noon indicium line(s) will be inclined to a vertical plane containing the gnomon at an angle equal to the difference between the longitude of the site and the longitude of the time zone meridian.

Abstract: A universal sundial which indicates watch time is constructed from a standard pipe section or cylinder with one end an elliptical plane at an angle to the axis of the cylinder preferably within approximately 15.degree. of the latitude of the proposed site. The gnomon is a small sphere located at the center of the elliptical plane end. Time, sun declination, latitude, and meridian displacement indicia are all located on the inner surface of the cylinder by angular coordinates from the center of the gnomon. Two cylinder or two removably attachable overlays are required for indication of civil time for a full year. The sundial is set up by orienting it so the shadow of the gnomon indicates the correct time when the gnomon is in a vertical position over the site latitude and meridian or meridian displacement indicia.