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Le livre sous recension porte sur les tables astronomiques produites dans une Europe latine délimitée, en amont, par le X e siècle et, en aval, par les premières décennies de l'imprimerie ; encore faut-il préciser qu'aux documents de l'espèce rédigés en latin, il ajoute ceux qui l'ont été dans d'autres langues pour peu qu'elles aient été pratiquées dans les bornes temporelles et spatiales ainsi posées-langue d'une minorité religieuse (l'hébreu) ou langues vernaculaires méridionales (le provençal, le catalan et le castillan). Le monde byzantin n'est abordé qu'indirectement, à la faveur de traductions en grec de tables conçues sur les territoires et durant la période en question. Il va sans dire qu'une telle tranche chronologique implique la prise en compte du Ptolémée arabo-latin et, plus largement, des traductions arabo-latines de textes d'astronomie, sans compter que les astronomes arabophones ont intégré à leurs travaux des éléments empruntés à ceux de leurs confrères indiens. Au final, on s'en doute, la configuration de l'Europe occidentale qui se dégage de ces pages est sensiblement différente de celle d'aujourd'hui. C'est une Europe dont Adélard de Bath avait énoncé les prémices intellectuelles en décrivant sa situation : « Ce que j'ai appris en arabe, je le noterai en latin » 1-une Europe donc qui, en s'ouvrant à des textes rédigés à l'extérieur de sa culture, acquérait peu à peu son autonomie savante tout en enrichissant sa propre identité. Dans ce transfert des savoirs,

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Computing the time from mean to true syzygy (conjunction or opposition of the Sun and the Moon) was one ofthe major issues addressed by medieval astronomers. Indeed, it was a difficult problem to which much ingenuity was devoted following Ptolemy's approximate solution (Almagest VIA). To our knowledge, the earliest solution to this problem in the form of a table appears in a work of the beginning of the twelfth century by Ibn al-Kammad.' It is a double argument table, the entries of which are given in terms of the difference between the hourly velocity of the two luminaries and the elongation between them. Some three centuries later, John of Gmunden (d. 1442), lecturer in astronomy at the University of Vienna, presented a simple way to compute the time from mean to true syzygy by means of a double argument table with the mean solar anomaly as vertical argument, and the mean lunar anomaly as horizontal argument.In an earlier paper;' we noted that "it is easy to derive this table from that of Nicholas de Heybech of Erfurt" (c. 14(0), the first astronomer to give a user-friendly presentation in tabular form of the solution to the problem of determining accurately the time from mean to true syzygy,3 thereby suggesting that the table presented by John of Gmunden was based in Nicholas de Heybech's table. New evidence shows that the transmission of this material occurred differently.Amongst the many works attributed to the French astronomer John of Murs (c. 1330),4 there is a short text entitled Tabulae permanentes consisting of a single table for finding the time of true syzygy, and a canon explaining its use. The incipit is: "Omnis utriusque sexus armoniam celestem ..", and the explicit: "... et habebis partem proporcionalem quesitam". The text of the Latin canon is transcribed in the Appendix, and we give an English translation. In most of the manuscripts containing this text, a colophon is added: "Expliciunt canones tabularum permanencium. lsta Johannes equat, cepit Firminus et implet. Lux gaudet, reprobat livor, amicus habet." These sentences may be translated as: "John has calculated these, Firmin has picked them up and completed them. The light rejoices, envy disapproves, a friend keeps them." The Firminus mentioned here is probably John of Murs's collaborator Firmin of Beauval. Note that John and Firmin participated in the conference on calendar reform convoked in Avignon under the auspices of Pope Clement VI (1342-1452) and in 1345 they made a joint proposal for the calendar reform to the Pope. During their stay at the papal court in Avignon both astronomers wrote prognostications for the triple conjunction of 1345. 5

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