GERBERTVS

International Academic Publication on History of Medieval Science

online journal

Editorial board: Flavio G. Nuvolone (Universite de Fribourg-CH) Paolo Rossi (University of Pisa-IT) Costantino Sigismondi (ICRA, International Center for Relativistic Astrophysics) Marta Materni (Sapienza University of Rome-IT)

submissions: email to sigismondi at icra.it

Vol. 1, 2010 Astronomy related papers: link and abstracts

C. Sigismondi,GERBERTVS una nuova rivista per l'astronomia e la scienza nell'alto medioevo, GERBERTVS vol. 1, pp. 1-2-295 (2010) Abstract: GERBERTVS appears as an international e-journal on medieval science, namely astronomy. It has been created to gather all the studia promoted on Gerbert of Aurillac, the most prominent figure of the tenth century: astronomer, organ builder and music theoretician, mathematician, philosopher, and finally pope with the name of Silvester II (999-1003). Here is presented the first volume (2010) published in the institutional web site www.icra.it/gerbertus with the ISSN 2038-355X.

C. Sigismondi, La Sfera di Gerberto, GERBERTVS vol. 1, pp. 3-15 (2010) Abstract: Gerbert describes a semi-sphere to Constantine of Fleury with built-in sighting tubes, used for astronomical observations. The procedure to identify the star nearest to the North Celestial Pole is very accurate. For didactical purposes the Polar Star would have been precise enough and much less time consuming, but here Gerbert is clearly aligning a precise equatorial mount which had to be logically set up as a fixed instrument for accurate daytime observations. Through the sighting tubes it was possible to detect equinoxes and solstices by observing the Sun in the corresponding days. This is the first time in which the full functionality of the sphere of Gerbert is put into evidence.

P. Rossi, Algoritmi matematici nelle lettere di Gerbert, GERBERTVS vol. 1, pp. 16-23 (2010) Abstract: The content of Gerbert's "scientific" letters is analyzed in detail, with special emphasis on arithmetical and geometrical issues, such as multiplication and division rules related to the use of abacus, superparticular numbers and evaluation of the area of an equilateral triangle. It is shown that Gerbert's area formula, albeit based on rational fractions, could hardly be conceived without knowledge of Pythagoras' theorem. This fact casts a light also on the astronomical tools created by Gerbert, where the didactical aspect cannot be separated from the accuracy of the demonstrations and of the measurements.

P. M. Maksym, Sylvester II Bukowiec Observatory: a "piece de theatre" for the inauguration day,GERBERTVS vol. 1, pp. 198-212 (2010) Abstract: The 21st of May 2010 has been the day of inauguration of the Astronomical Observatory of Bukowiec "Pope Sylvester II". This observatory, a fixed station of the European network of asteroidal and lunar occultations for high resolution astrometry, is built in the territory of the school dedicated to Nicolas Copernicus, the most famous polish astronomer. This new observatory starts its activity in the international year of astronomy, which celebrates the 400th anniversary of the astronomical use of the telescope by Galileo Galilei. The polish astronomer Bohdan Paczy?ski is the fourth protagonist of the pièce théatrale written for the day of inauguration. Here is reported the text of this pièce, which was a powerful way to introduce people to the knowledge of Sylvester II, great scholar and teacher of the 10th century, who founded the first diocesis in Poland when he was Pope.

J. N. Silva, Mathematical games in Europe around the year 1000,GERBERTVS vol. 1, pp. 213-225 (2010) Abstract: There are strong reasons to relate Gerbert with games as it is shown in my text "Teaching and playing 1000 years ago, Rithmomachia". This paper addresses the question: which board games could Gerbert have played? There are also astronomical games.

G. De Dona', Nicola Cusano e il foro astronomico al castello di Andraz,GERBERTVS vol. 1, pp. 251-269 (2010) Abstract: Cardinal Nicolas from Cues (1401-1464) was friend of Paolo Toscanelli and one of the first supporters of heliocentrism. He carved a tube in the south western wall of a room of the castle of Andraz. It was possibly used to calculate the date of the winter solstice, in order to evaluate the corrections needed to the Julian calendar then in use. The astronomical use of this tube is described. The accuracy achievable in the measurement of the solstice is surprising. It is possible that the tubes made by Gerbert of Aurillac (945-1003) were used with similar awareness.

C. Sigismondi, Gerberto, gli Arabi e Gerusalemme, GERBERTVS vol. 1, pp. 270-294 (2010) Abstract: Gerbert of Aurillac went in Catalonia from 967 to 970, to visit the bishop Atton of Vic, famous for mathematical knowledge, during the apogee of Cordova's reign of the Caliph Al-Hakam II ibn Abd al-Rahman (961-976). He maintained contacts with local personalities like Mirò Bonfill (Bishop of Girona) and Lupitus of Barcelona through letters (both dated 984). When he was pope, Gerbert sent five papal privileges to Catalan dignitaries, showing his attention to this territory. The Caliph's prime minister Al-Mansu'r depredated Barcelona in 985, and conquered Santiago de Compostela in 997, drawing to an end the cultural exchanges between Christian and Arabic world through Mozarabic and Jewish translators. Gerbert learned and after taught and used Indo-Arabic numbers, abaci, astrolabes, monochords and theoretical music. It was possible for pilgrims to reach Jerusalem at Gerbert's times, and a letter written by Gerbert probably for an abbot starting his pilgrimage seems to introduce the first ideas of crusade and indulgences related to offers. The change of attitude of the Al-Andalus' government toward Christianity is probably responsible of these words written in a time very close to the depredations of Barcelona. Jerusalem is also in the index of geographic places in the book of the astrolabe, attributed to Gerbert, as well as Santiago de Compostela. Finally the legend of the Golem and the mass celebrated in the church of Jerusalem in Rome, completes the panorama of Gerbert and the Holy City.