Dominican Republic 1932. Batwing Sundial Erected in 1753. 10c. Sc# C11. Used

Description

A
sundial
is a horological device that tells the time of day (in modern usage referred to as
civil time
) when there is sunlight by the apparent
position of the Sun
in the sky. In the narrowest sense of the word, it consists of a flat plate (the
dial
) and a
gnomon
, which casts a shadow onto the dial. As the
Sun appears to move across the sky
, the shadow aligns with different hour-lines, which are marked on the dial to indicate the time of day. The
style
is the time-telling edge of the gnomon, though a single point or
nodus
may be used. The gnomon casts a broad shadow; the shadow of the style shows the time. The gnomon may be a rod, wire, or elaborately decorated metal casting. The style must be
parallel to the axis
of the
Earth's rotation
for the sundial to be accurate throughout the year. The style's angle from horizontal is equal to the sundial's geographical
latitude
.