Giovanni Francesco Zarbula

Giovanni Francesco Zarbula was a mural painter and sundial designer from Piedmont Italy who created a hundred or more vertical and vertical declining sundials in the French and Italian Alpes between 1830 and 1881. He worked exclusively in Savoy, in Piémont, the Valley of the Ubaye, le Queyras and around Briançon. [1]

1840

Laying out the dial

Zarbula's method was one of observation then geometric construction. He did not need to know the latitude or declination of the wall, he did not use tables or calculations he just worked directly on the wall. All his dial were within 2° of the 45th parallel, simplifying the construction, and all gave five-minute accuracy.

  • With a plumb bob he drew a vertical line on the wall. This is the "Noon Line".
  • He hammered a rod into the wall at right angles to the vertical. This is known as the "centre of the dial", or C
  • He observed and marked the shadow thrown by the tip of that rod, throughout a day. This line, technically known as a hyperbolic declination line.[lower-alpha 1]
  • Using a set of compasses, he determines the line of symmetry on the wall.[lower-alpha 2] This is the "substyle line".[lower-alpha 3]

All the rest of the dial was laid out using a 45° square, with a 15° measure at the end. [lower-alpha 4]

  • He drew a horizontal line at a point of choice on the dial plate. This was the "Horizon".
  • The square was placed on the substyle facing outwards, it is slid into any convenient position where it cuts the horizon, and he drew a perpendicular line drawn to that point. This line is called the "equatorial". A line was drawn from that point to the centre of the dial; it was the 18h line (or 6h depending on the declination (d) of the wall). The points where the equatorial crosses the noon line and where the equatorial crosses the substyle line were important.
  • He placed apex of the square on the substyle line, so the sides passed through the equatorial points mentioned. (The 12h and 18h markers). The apex point is called the "auxiliary equatorial centre".
  • A protractor or squares [lower-alpha 5] drew off 15° intervals on the equatorial. These were connected to the centre of the dial: the hour lines. The distance from the auxiliary equatorial centre to the equatorial formed the substyle height at that point.[2][3]

The colours

Zarbula treated his paintings as frescos so the body colour was embedded in the supporting lime mortar. He didn't use organic pigments, just oxides. These do not fade in the strong alpine sunlight.

Existing Dials (cadrans)

Of the hundred dials by Zarbula, about 50 have survived, and a further dozen show visible traces.[4] In Hautes-Alpes, seven dials are protected as monument historique.[5]

His dials can be divided into three specific styles Öiseau (Birds), Geometric, Baroque. The birds that appear in the dials of the early 1840s include toucans, jabirus, parakeets and other exotic birds not seen in these mountains. The geometric works of the late 1840s and 1850s are noted or their simplicity, and contain a little trompe-l'œil to give the design some artificial depth. The baroque dials are contain birds, vases, full trompe-l'œil and false-marbling. They contain the symbols of the Second Empire (1852-1870) and Napoleon III particularly the Imperial Eagle. The dials produced after 1865 include the Masonic device of the Square and Compasses: this is co-incidental to the rise and acceptance of masonry on both sides of the Italian French border.[6]

Commune/Village Lieu-dit/Hameau/Hamlet Édifice Region Country Date Protection Notes Coords. Illus.
Briançon Saint-Blaise Briançonnais France 1870 Deux cadrans 44°52′34″N 6°36′48″E
Briançon Place d'Armes Centre d'art contemporain Briançonnais France 1876 Peut-être inspiré de Zarbula 44°53′56″N 6°38′34″E
Briançon Saint-Blaise Briançonnais France 1870 44°52′33″N 6°36′49″E
Briançon Pont-de-Cervières, 4 chemin du Canal-du-Four Briançonnais France 1845 44°53′11″N 6°38′16″E
Cervières Maison Delouis Briançonnais France 1839 Base Mérimée: PA05000001, Ministère français de la Culture. (in French) Deux cadrans 44°52′11″N 6°43′22″E
Cervières Hôtel de ville Briançonnais France 44°52′10″N 6°43′14″E
Eygliers Le Cros Briançonnais France 1841 44°40′55″N 6°37′28″E
La Salle-les-Alpes Les Pananches Chapelle Saint-Jean-Baptiste Briançonnais France 1879 Attribué à Zarbula 44°56′22″N 6°34′57″E
La Salle-les-Alpes 38 rue de la Guisane Briançonnais France 1841 44°56′44″N 6°33′47″E
Puy-Saint-André Pierre-Feu Briançonnais France 1871 44°52′18″N 6°36′00″E
Puy-Saint-André Briançonnais France 44°52′45″N 6°35′57″E
Puy-Saint-Pierre Le Pinet, 2 rue de Jérusalem Briançonnais France 1842 Base Mérimée: PA00135605, Ministère français de la Culture. (in French) Deux cadrans 44°53′26″N 6°37′31″E
Saint-Chaffrey Le Villard-Laté, 27 rue des Trois-Fontaines Briançonnais France 1847 Base Mérimée: PA00135607, Ministère français de la Culture. (in French) 44°56′12″N 6°35′40″E
Saint-Martin-de-Queyrières Bouchier Briançonnais France 1853 44°49′58″N 6°33′57″E
Saint-Martin-de-Queyrières Prelles Briançonnais France 1845 44°51′17″N 6°34′51″E
Saint-Martin-de-Queyrières Prelles Briançonnais France 44°51′14″N 6°34′49″E
Saint-Martin-de-Queyrières Église Saint-Martin Briançonnais France 44°50′25″N 6°35′07″E
Les Orres Le Mélezet Église Notre-Dame-de-la-Présentation des Orres Les Orres France 1853 Base Mérimée: PA05000006, Ministère français de la Culture. (in French) 44°30′18″N 6°33′12″E
Arvieux Le Coin Maison Jean-Paul Blanc Queyras France 1830 Superposition de cadrans, l'un d'eux pouvant être de Zarbula 44°46′21″N 6°43′58″E
Arvieux Queyras France 1857 44°46′01″N 6°44′19″E
Arvieux Les Escoyères Queyras France 1842 44°43′08″N 6°44′39″E
Arvieux Les Escoyères Chapelle Saint-Roch Queyras France 1857 44°43′06″N 6°44′35″E
Château-Ville-Vieille Ville-Vieille Queyras France Attribué à Zarbula 44°45′23″N 6°47′22″E
Château-Ville-Vieille Clot-du-Riou Queyras France Base Mérimée: PA00135602, Ministère français de la Culture. (in French) Deux cadrans 44°45′54″N 6°46′44″E
Château-Ville-Vieille Ville-Vieille Église Saint-André de Château-Ville-Vieille Queyras France 1843 44°45′36″N 6°49′19″E
Château-Ville-Vieille Ville-Vieille Queyras France 1843 44°45′26″N 6°47′38″E
Château-Ville-Vieille La Rua Queyras France 44°45′37″N 6°49′10″E
Molines-en-Queyras La Rua Église Saint-Romain Queyras France 1849 44°43′53″N 6°50′20″E
Saint-Véran Les Forannes, la Pointe du Jour Queyras France 1840 Base Mérimée: PA05000004, Ministère français de la Culture. (in French) 44°42′06″N 6°51′58″E
Saint-Véran La Raux Queyras France 1840 44°41′54″N 6°51′45″E
Saint-Véran Ferme de Mathieu Romain Queyras France 1840 44°41′59″N 6°52′06″E
Saint-Véran Haut-Forranes Queyras France 1840 44°42′11″N 6°51′54″E
Saint-Véran Pierre-Belle Queyras France 1840 44°41′55″N 6°52′09″E
Saint-Véran Les Gabelous Ancienne douane Queyras France 1858 44°41′57″N 6°52′12″E
Saint-Paul-sur-Ubaye Petite-Serennes Ubaye France 1860 44°31′44″N 6°46′28″E
Saint-Paul-sur-Ubaye Maljasset Ubaye France 1860 44°35′34″N 6°50′35″E
Pragela Souchères Basses Chapelle Val Cluson Italie 1872 45°01′47″N 6°57′39″E
Pragela Traverse, 6 via Nazionale Val Cluson Italie 45°00′00″N 6°55′34″E
Pragela Villarmont Val Cluson Italie 1872 45°00′01″N 6°55′00″E
Sauze di Cesana Rollieres Chapelle Val Cluson Italie 1870 Deux cadrans 44°56′15″N 6°49′56″E
Sestrières Champlas du Col, 28 via Nazionale Val Cluson Italie 1870 44°56′51″N 6°51′06″E
Sestrières Champlas du Col, 7 via Nazionale Val Cluson Italie 1870 44°56′52″N 6°51′10″E
Sestrières Borgata Val Cluson Italie 1872 44°58′20″N 6°53′44″E
Sestrières Borgata, 14 via del Colle Val Cluson Italie 1872 44°58′20″N 6°53′45″E
Sestrières Borgata, 12a via del Colle Val Cluson Italie 1872 44°58′19″N 6°53′44″E
Usseaux Balboutet Val Cluson Italie 1833 Deux cadrans 45°03′07″N 7°00′49″E
Névache Ville-Haute Église Saint-Marcellin de Névache Vallée de la Clarée France 45°01′08″N 6°36′17″E
Val-des-Prés Pra-Premier Vallée de la Clarée France 1843 Base Mérimée: PA00135609, Ministère français de la Culture. (in French) 44°57′06″N 6°40′32″E
Val-des-Prés La Vachette Vallée de la Clarée France 1840 44°55′03″N 6°40′31″E
Val-des-Prés La Vachette Vallée de la Clarée France 1852 44°55′00″N 6°40′26″E
Valloire Valloire France 45°09′55″N 6°25′39″E
Valloire Les Verneys Valloire France 45°08′59″N 6°25′14″E
Vallouise Maison de Bardonèche Vallouise France 1840 Base Palissy: IM05003855, Ministère français de la Culture. (in French) Deux cadrans 44°50′40″N 6°29′08″E
Vallouise Le Villard Chapelle Saint-Sébastien Vallouise France 1869 Base Palissy: IM05003852, Ministère français de la Culture. (in French) Deux cadrans 44°50′30″N 6°28′22″E
Valserres Les Trancs France 1854 44°29′30″N 6°07′24″E

References
Footnotes
  1. Declination of the sun ( δ ) not declination of the wall (d)
  2. Indian or Hindu Circle for Sub-style determination
  3. In dialling language substyle is used like sub aqua, meaning- under the style- not like subsection, meaning a smaller part. Similarly, equation means an adjustment and height can mean a perpendicular angle.
  4. Zarbula was working within 2° of the 45th parallel, so it worked. Further north or south the triangle would need to use the latitude and co-latitude and a protractor would have been needed
  5. A combination of a 30°/ 60° square, and 45° square could also be used.
References
  1. Les Cadrans solaires (ed.). "Giovanni Francesco Zarbula".
  2. http://www.ens-lyon.fr/RELIE/Cadrans/Promenades/Zarbula/Equerre
  3. Paul Gagnaire. "L'Équerre et l'Oiseau, l'Art et la Manière de Zarbula".
  4. Les Cadrans solaires (ed.). "La Technique de G. F. Zarbula".
  5. "Cadrans solaires de Zarbula protégés aux monuments historiques". Base Mérimée.
  6. Les Cadrans solaires (ed.). "La Style de G. F. Zarbula".


This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.