TYPES OF SUNDIALS
Equatorial sundials
Gnomon is parallel to the Earth's rotation axis, thus, it points to the North Pole. For the Northern hemisphere this direction is near the North star in the constellation Ursa Minor (error is less than 1°). Dial surface is parallel to equator's plane and perpendicular to gnomon.
To construct equatorial dial we need to divide a circle into 24 equal sectors of 15° each. It can be easily done with old good pair: compasses and ruler.
It is necessary to mark the upper part of the dial in a clockwise direction, and the bottom surface - clockwise.
Equatorial sundials are universal and may be used in any place on the Earth, if mounted properly. It means, that gnomon should be pointed to celestial Pole, while 6-18 hour line should be horizontal.
Being two-sided equatorial sundial actually has two mirror-symmetrical dials for time-reading in summer and winter time. At equinox days Sun lays in the dial's plane.