Abstracts of the latest edition of Orologi Solari
ABSTRACTS
Altitude sundial in Este Paolo Albéri Auber The altitude (Shepherds') dial was already known in the age of Rome. Near Este (PD) in the so called "doctor's grave" a very interesting find was discovered in the 19th Century. In 2007 I recalculated the original latitude. The main steps in this recalculation are here summarized. A similar find was recently discovered at a latitude not far from the computed one.
Paper sundials Riccardo Anselmi Paper sundials represent an instructive pastime in which the passion and patience are critical to the success of this new outstanding gnomonic initiative on Sundial Atlas. Here we describe some of paper sundials presented on Sundial Atlas, chosen among the most interesting ones.
Developing a reflection sundial Gianpiero Casalegno The author describes his experience in designing and building a reflection sundial and tells how, contrary to what it is usually thought, this may be even easier that making a classical sundial.
Sundial design from the measurement of two shadow points Francesco Caviglia A method is presented to design a sundial on whichever flat surface, with unknown orientation, based on the evaluation of two shadow points measured at known different time instants. The method is based on the study of the rotation matrix that transforms the sun rays direction vector from the local equatorial system to a system based on the sundial surface. The method can also easily supply the parameters that characterize the orientation (declination and inclination) of the surface under evaluation.
"Projective" sundials laboratory (part 1) Francesc Clarą The author presents a category of solar clocks by him called "projective"and describes, in this first part of the article, the calculation and practical construction of one of these watches. The watch taken into consideration has a linear scale of hours and a movable gnomon, placed on a horizontal base.
The Julian Easter (part 1) Giuseppe De Doną In this work, the author analyzes the main phases that led Christian communities to define the rules related to Easter in the Julian calendar and applied until the Gregorian reform in 1582. Some ideas are maybe, not well known as, being that calendar no longer in use since more than 400 years, some characteristics have been necessarily lost or they were neglected by the authors who debated this topic. At the end of the article the author reflects about the date of birth of Christ
An ingenious altitude sundial of guaranteed failure: the "universal"clock by John Marke (1641 - 1673) Alessandro Gunella The article examines a "universal" altitude dial, built in the 17th century by J. Marke, showing that its characteristics and its performances reflect exactly the scheme of the Analemma. The author pauses explaining how the instrument must be prepared introducing the elements related to latitude, date, height of the Sun at the sixth hour. He concludes that this is a high quality tool that however requires diligence and preparation from the user: ergo, a tool with no future.
A sundial on a pyramid Milo Nosek The following article describes the gnomonic system winning the XIII edition of the competition "Le ombre del tempo" and designed by Milo Nozek, from the Czech Republic, in Malż Smokovec at the foot of the Alti Tatra mountains in the Slovakian Republic.
The Waldshut Apolyearth (part 1) Ives Opizzo The new characteristics of the Waldshut Apolyearth are here explained. This instrument, in the middle between gnomonics and astronomy, won the professional category award of the XII edition of the international competition "Le Ombre del Tempo" established by the Unione Astrofili Bresciani and the Severino Zari Observatory. The author debates from the didactical point of view a number of simple astronomic concepts and he then deduces some humanistic results.
"Operating with the operating nature" The Flora clock in Bacoli (NA) Ennia Visentin A horizontal flower sundial, installed inside of a garden in a structure dedicated to host events, is described with poetical tones.