Sun dial

Like the sun charts, the sun dial is based on projecting the sun paths onto a surface. In this case they are projected onto different surfaces by tilting the four sides of the sun dial. Since the projections are dependent upon the degree of latitude, different sun dials are needed depending on the degree of latitude on which the construction project lies.

Depending on the incline of the sun dial, the shadow of the needle head shows the required point in time (month and time of day), in this case 12:00 midday on 21st March or September.

Cone-shaped sun dials with degrees of latitude that are accurate to the arc minute are available from the Institut für Tageslichttechnik Stuttgart (link).