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  • Al Cibart di Carrara (dal n. 667 L'Informatore del Marmista)
  • Macchine virtuose (dal n. 667 L'Informatore del Marmista)
  • Realtà virtuale (dal n. 669 L'Informatore del Marmista)
  • Marmo Rosso Verona per la Maternità (dal n. 669 L'Informatore del Marmista)
Al Cibart di Carrara (dal n. 667 L'Informatore del Marmista)

Al Cibart di Carrara (dal n. 667 L'Informatore del Marmista)

Macchine virtuose  (dal n. 667 L'Informatore del Marmista)

Macchine virtuose (dal n. 667 L'Informatore del Marmista)

Realtà virtuale (dal n. 669 L'Informatore del Marmista)

Realtà virtuale (dal n. 669 L'Informatore del Marmista)

Marmo Rosso Verona per la Maternità  (dal n. 669 L'Informatore del  Marmista)

Marmo Rosso Verona per la Maternità (dal n. 669 L'Informatore del Marmista)



CONTENTS 
EVENTS Carrara Marble Week: sculpture, design, architecture  | The German stone industry appointment  TOWN PLANNING Measuring time with Montorfano granite SCULPTURE Kan Yasuda manages to ...touch time | Black Sea sculpture symposium | The works of Ponzanelli in the Basilica of the Saint ARCHITECTURE The "intense" architecture of Francisco Mangado COLUMNS Cultural events | Exhibitions | Classified advertisements | Notes

Article of the month
Measuring time with Montorfano Granite by Giacomo Bernardelli
Measuring time with Montorfano Granite “I make sun dials because stone, for me, comes alive when a gnomon caresses it indicating the time and the seasons with incredible precision... May I mention how I work: with love and passion”: Rodolfo Piralla has made sun dials for many years using Montorfano white granite, a uniform medium-large grain material with a uniform light colour generated by white feldspar and very low biotite content, from the quarries in Mergozzo (Verbania). A granite sun dial standing in a garden rivals the beauty of any statue or fountain, inspiring peace and a spirit of contemplation that qualifies its owner as someone who cares about nature and the cosmos. A sun dial, in short, is like a tiny mirror of the celestial sphere faithfully reproducing the phenomena taking place in it. “Setting up a sun dial in your garden, - Rodolfo Piralla goes on, - means resuming control over your time, your real time, spent looking after the people and the things we love, released from the tyranny of time calculated down to a thousandth of a second that modern life at times imposes on us. Observing time as the movement of a shadow over of a sun dial is in any case a philosophical experience, a travel based on calmness and perfect harmony with one’s own circadian rhythms, an almost mystical experience for those who wish and can appreciate it”. Rodolfo Piralla’s sun dials are to be found in private gardens as well as public places, such as Loano Marina (Savona), where the sun dial titled “Vela di Loano” is located. It is a “dual polar dial”: the face of the dial is defined as “polar” because the gnomons point precisely to the Pole Star and are parallel to the Earth’s axis of rotation. How it works can be summed up as follows: when the sun comes up, the east face is illuminated so that solar time can be read until 11 am. Afterwards, the light becomes extremely “radiant” making it difficult to read the time, so that the a “light point” hourly semi-circle was set into the slanted part, used to indicate time between the solar noon, i.e. between 11 am and 1 pm. From 1 pm, it is possible to read the west dial, which indicates the time through to sunset. A “noon hole” was incorporated, essentially having an informative and curious purpose, since it is easy to read and immediately understood. The instant of true solar noon (when the sun is precisely South) is easily identified as the instant when the entire interior of the hole is completely in shadow. The solstitial hyperboles indicate the passage of the shadow respectively on 21 June (day with the most hours of sunlight) and 22 December (day with the fewest hours of sunlight). The groove on the slanted part of a value equal to the latitude of Loano makes it possible at night to collimate the Pole Star. The horizontal yellow line with the wording “Sunrise” on the East face and “Sunset” on the West face ensures easy and intuitive interpolation of these times for every day of the year. The work, carved from an enbloc of Montorfano granite, measures: 395 cm in height x 160 cm in width x 20 cm in thickness. It weighs about 2.50 kg. The East and West faces are polished, while the South and North faces are bush-hammered. The equatorial sun dial with rotating discs named “Hours around the World” is also impressive. This instrument has two rotary discs that, used together with the table on the foot of the dial, can be used to calculate the time anywhere n the world. It suffices to read the number of hours ahead or behind from a place for which one wishes to know the time of day from the table and then turn the disc by the correct number of hours. The equatorial sun dial changes its dial during year, then: from March to September, the upper face is illuminated and from October to February the lower face. This equatorial sun dial includes the table with the time equation and details recalling the sun. This is also a universal instrument: simply by slanting the support by 90° less the latitude, the readout is correct at the equator as at the Poles. The “San Salvador” equatorial sun dial has the unusual characteristic of illuminating its two faces in alternation for 6 months each year. From 21 March to 22 September, the upper face is illuminated, from 22 September to 21 March the lower face. A light bridge indicates the time and the season. The sphere at the front represents the Earth at the latitude of the place where the dial is installed. The sphere is the mirror of everything that happens on the Earth during the seasons. Rodolfo Piralla's sun dials are produced by Piralla Graniti Co. in Mergozzo (Verbania), that specialises in processing Montorfano white granite, serizzo and beola stones, Baveno granite pink, Crevoladossola Marble and other Italian stone materials.

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