Free Astronomy Magazine March-April 2022

44 MARCH-APRIL 2022 ASTRO PUBLISHING A “landscape” sundial painted on wood, whose stylus is represented by one of the ski poles! Pragelato, Sestriere (Italy). [Photo FB] working in the fields, but whose du- ration varied between summer and winter. The direction of dawn al- lowed us to orient ourselves across the seasons and to know when to sow or harvest. A simple stick planted vertically in the horizontal ground already al- lows you to identify the direction of sunrise and sunset and to count the hours during the day. This device is a gnomon, the ancestor of sundials. The origin of sundials is lost to an- tiquity and probably dates back more than 2000 years. After the sim- ple gnomon, the first sundials took the form of either a sphere carved into stone, whose hour lines were spaced 15° (360°/24h) apart, or a ver- tical sundial with a straight stylus that allowed one to identify the times of prayer, called a canonical sundial. Sundials subsequently be- came more sophisticated, with the appearance of the polar style, the Babylonian and Italic hours, diurnal arcs, and many other ways of marking certain infor- mation related to the Sun. Some countries are distin- guished by the large num- ber of ancient sundials that were created there: in par- ticular, Italy, France, and England. Most of these sundials are now restored and are considered as real elements of the architec- tural and artistic heritage of their hosting cities. It is enough to spend a few days in many Italian cities, in Saint-Véran in the French Alps, in Oxford in England, or in Prague in the Czech Republic, to see magnificent sundials on many street corners. Several famous museums have very nice collections of portable or decorative T he vertical sundial of Guedoz House, in Abbé Henry Square, in Courmayeur (Italy), de- signed and built by Captain Enrico Alberto D’Albertis in 1920. Deteriorated by the pas- sage of time and urban transformations, this sundial was restored in 2017 based on the original designs. Among the fifteen sundials present in the territory of Courmayeur, this is the most historically important one. [Photo MF]