The Swedish runic calendar or almanac is a medieval invention, based on the nineteen year long metonic cycle of the moon. The runic calendars had a revival in the eighteenth century, as seen here in our newly acquired 1784 almanac. Its foldout shows a Runic calendar translated to a modern alphabet. Special days like solstices, equinoxes, and celebrations were marked with additional lines of symbols.
According to Arild Hauge, “The runes could be written from left to right or right to left. They also could be written with the first sentence proceeding right to left and the second sentence proceeding left to right … The runes could be written in all kinds of directions and upon almost any kind of common material—as beautiful decorations or as a hidden, magic formula …”
Because this system needed nineteen runes to represent the nineteen golden numbers that stood for the nineteen years of the perpetual calendar’s cycle, three additional characters were added to the traditional runic alphabet of sixteen characters. A sixteen character set can be found here: http://www.arild-hauge.com/esruner.htm.
An earlier runic wood staff can be seen at http://rmc.library.cornell.edu/Paper-exhibit/runic.html.
Just for fun, writing your name in runes: http://www.pbs.org/wgbh/nova/vikings/runes.html.