Disegnare il tempo. Rocco Bovi e gli orologi solari della Certosa di San Martino/Drawing time. Rocco Bovi and the San Martino Charterhouse sundials

Sundials are no more than the graphical representation, on Earth, of the apparent motion that the Sun that runs along the surface of an ethereal celestial sphere. This drawing is obtained by projecting those straight light rays that align the different positions of the Sun with the tip of the gnomon and the shadow on the dial. This immaterial contact between Heaven and Earth is a charming timeless element that makes even today sundials a natural meeting place for art, philosophy, geometry, geography, physics and astronomy. These precious artistic objects, often located in monumental architectures, are the memory of an ancient and valuable knowledge of centuries when humans regulated their own activities in close connection with the natural and astronomical time sequences during the day and the whole year. Measuring the time and observing its eternal cycles, conditioned for centuries the daily habits of the community, but also rites and liturgies of all religions, based on the periodic repetitiveness of celestial phenomena. Sundials are graphic evidence on the Earth of complex astronomical events, always in progress on the celestial sphere at infinite distances from us, and their execution was often characterized by the convergence of various doctrines, from mathematics to physics, geography, cartography, geometry art, testifying to the fervent cultural climate has arisen in Europe between the Fifteenth and Nineteenth centuries. In this rich intellectual scenario, Italy and the Campania region in particular, boast the realization of several sundials of great artistic and scientific value, inadequately valorized for the progressive dispersion of this ancient culture due to the advent of modern watches. Between the negligence and the inability to carry out adequate restorations, Neapolitan sundials constitute a cultural heritage to be saved with urgent actions for the protection and recovery, based on the dissemination of their value that, in the "city of the sun", could trigger interesting processes of teaching and tourism disclosure. Some of those are in clear state of degradation, have been lost to other lines on the dial as in the refined vertical sundials in the Floridiana and in the Certosa di San Martino (of which there are fortunately ortostili fixtures in the facade), and others have suffered inappropriate restoration work that have altered the system of measuring time. Some of those are in clear state of degradation, have been lost to other lines on the dial as in the refined vertical sundials in Floridiana and in Carthusian monastery of San Martino (of which there are fortunately the perpendicular styles fixed in the facade), and others have suffered inappropriate restoration works that have altered the original system of measuring time. In addition to numerous ancient examples, in Naples there are some interesting contemporaries sundials, not adequately exploited, as the analemnatic one in front of the railway station of Mergellina and the Tower of the arch. Massimo Pica Ciamarra in Piazzale Tecchio (scientific project of Edgardo Filippone). Sundials are no more than the graphical representation, on Earth, of the apparent motion that the Sun that runs along the surface of an ethereal celestial sphere. This drawing is obtained by projecting those straight light rays that align the different positions of the Sun with the tip of the gnomon and the shadow on the dial. This immaterial contact between Heaven and Earth is a charming timeless element that makes even today sundials a natural meeting place for art, philosophy, geometry, geography, physics and astronomy. These precious artistic objects, often located in monumental architectures, are the memory of an ancient and valuable knowledge of centuries when humans regulated their own activities in close connection with the natural and astronomical time sequences during the day and the whole year. Measuring the time and observing its eternal cycles, conditioned for centuries the daily habits of the community, but also rites and liturgies of all religions, based on the periodic repetitiveness of celestial phenomena. Sundials are graphic evidence on the Earth of complex astronomical events, always in progress on the celestial sphere at infinite distances from us, and their execution was often characterized by the convergence of various doctrines, from mathematics to physics, geography, cartography, geometry art, testifying to the fervent cultural climate has arisen in Europe between the Fifteenth and Nineteenth centuries. In this rich intellectual scenario, Italy and the Campania region in particular, boast the realization of several sundials of great artistic and scientific value, inadequately valorized for the progressive dispersion of this ancient culture due to the advent of modern watches. Between the negligence and the inability to carry out adequate restorations, Neapolitan sundials constitute a cultural heritage to be saved with urgent actions for the protection and recovery, based on the dissemination of their value that, in the "city of the sun", could trigger interesting processes of teaching and tourism disclosure. Some of those are in clear state of degradation, have been lost to other lines on the dial as in the refined vertical sundials in the Floridiana and in the Certosa di San Martino (of which there are fortunately ortostili fixtures in the facade), and others have suffered inappropriate restoration work that have altered the system of measuring time. Some of those are in clear state of degradation, have been lost to other lines on the dial as in the refined vertical sundials in Floridiana and in Carthusian monastery of San Martino (of which there are fortunately the perpendicular styles fixed in the facade), and others have suffered inappropriate restoration works that have altered the original system of measuring time. In addition to numerous ancient examples, in Naples there are some interesting contemporaries sundials, not adequately exploited, as the analemnatic one in front of the railway station of Mergellina and the Tower of the arch. Massimo Pica Ciamarra in Piazzale Tecchio (scientific project of Edgardo Filippone). A good enhancement project of sundials must necessarily start from the knowledge, in order to achieve conservation, improvement and promotion laying the foundations for their subsequent use. The current study has thus identified a methodology able to establish a dialogue between different fields of knowledge (restoration, geometry, new technology, history of architecture, astronomy and gnomonic) with the main purpose of triggering the disclosure, the communication and the consequent use of these singular artistic goods, very often abandoned through their own recovery and development. The work we present provides for the re-functioning and restoration of three sundials in the Carthusian monastery of San Martino in Naples and the establishment of a specific exposition to facilitate their dissemination, based on the most modern digital technology. In the Carthusian monastery of San Martino in Naples it is possible even today to observe three very valuable sundials; The first, and most famous, is the meridian line clock which is located in the Prior Quarter, built in 1771 by Rocco Bovi, one of the most unique and complicated examples of its kind for the artistic drawing of the bronze bands, the amount of astronomical, geometrical and geographical information providing in the vast net of readable data and for placement in a prestigious architecture, which is so closely connected with the meridian line to be considered an integral part of the gnomonic project. The meridian sundial is now well preserved inside the ex library of the Prior but equally poorly appreciated: despite his immeasurable value gnomonic, which places it among the most complex sundials ever made in Campania does not exist an exhibition as to make it communicable, and therefore appreciable. The architecture of the room actively collaborates with the clock hosted in its interior: the bronze band is set in a beautiful terracotta tiled floor in riggiole by the artist Leonardo Chiaiese that shows correctly, on the horizontal plane, the projection of the curves of the tropics and the straight line of the equator, as well as a singular disposition of constellations of both hemispheres, which appears as derived from the ancient representations of the cosmos, including the Farnese Atlas globe. The exterior windowsill in which is located in the gnomonic hole, also has a peculiar splay, totally absent in the other adjacent openings the architectural complex, built in order to accommodate the entry of sunlight. A superelevation made in the same Charterhouse during the nineteenth century made it impossible for the light to reach the gnomonic hole during the winter months, when the height of the Sun on the celestial plane of the horizon is lower, with the unpleasant result that, just at the date of the winter solstice, clearly delineated by an ellipse with finely engraved in the band of bronze, the Sun cannot project its macular bright on the sundial line. Our surveys also revealed that the gnomonic hole present on the wooden platband of the entrance door needs a more appropriate placement to correct some height changes due to restoration work that have occurred over the centuries. Our research has therefore approached the project of re-functioning of the sundial through a system of mirrors placed on the roof of the building in front of the library in order to re-direct solar rays inside the gnomonic hole in those months in which the height of the sun is not that height on to the plane of the horizon. The second sundial is located in the big cloister but the time lines have been erased from the first years of the twentieth century; the dial is banally plastered although it is still present a perpendicular style fixed in the wall, that still casts its shadow without measuring the time anymore. From documentary and iconographic sources it has been possible to us to reconstruct the lost lines of the solar clock and therefore to propose its reactivation. The third sundial present in the Charterhouse is a unique example of multiple dial carved in marble, in which are found the most ancient systems of chronometry like a Babylonian and Italian hours. Poorly appreciated for the lack of an opportune exhibition in the museum, the clock no longer performs its function for the total absence of the gnomons, for which it is proposed an intervention of restoration of lost stylus according to the dimensions determined, for each quadrant, with a geometric method. We intend, therefore, to bring back to light an ancient knowledge, now under dispersion, starting from some of its best examples, for gnomonic complexity and placement because they are situated in one of the most important Italian museum, able to attract significant group of tourist and so responsible of a large cultural diffusion. Reactivating the lost function of measuring the time, but mainly creating a new and more appropriate representation model sundials could still now communicate allows the complexity of astronomical phenomena connected to them. The entire research was conducted with a dual method, weaving astronomy and gnomonic with the geometry, for the construction of a three-dimensional model to verify and plan sundials restoration, for which, however, were indispensable historical and documentary researches that we conducted in the most Italian archives, thanks to which we could interpret the real intention of the author, testified directly by the the original manuscripts we found in Neaples, by the newspapers of the time, but also by the correspondence that Rocco Bovi maintained with eminent figures of its cultural scene containing descriptions indispensable for a correct reading of the analyzed information. For example, the geographical locations engraved along the side bands of the sundial, each showing an angular value in correspondence, have been correctly identified, despite the initial ambiguity due to their ancient nomenclature, thanks to the explanation of Bovi himself who, in the manuscript – totally analyzed in the third chapter -, describes them as places with the same midday of Naples, and which are therefore to be placed along the same terrestrial meridian.