John of Murs Revisited: The Kalendarium Solis Et Lune for 1321

The astronomical work of John of Murs (fl. 1320-40), a scholar born in Normandy and active in Paris in the first half of the fourteenth century, has received extensive attention in recent years, both as an early transmitter of the Alfonsine Tables elaborated in Toledo in the late thirteenth century and as one of the compilers of tables based on them, known as the Parisian Alfonsine Tables, that were widely diffused throughout Europe from the fourteenth to the sixteenth century.1 Among John of Murs's astronomical works are the following:(1) The Expositio intentionis regis Alfonsii circa tabulas eius, a text with no tables, probably composed in 1321, where he praises the Alfonsine Tables and states explicitly his dependence on them.2(2) The Tables of 1321, his first and most extensive set of tables, with a text beginning Si vera loca planetarum per presentes tabulas volueris invenire. . . . The tables are devoted to the five planets as well as the Sun and the Moon, but nothing related to the daily rotation and trigonometry is addressed.3(3) The Patefit, a work composed of tables for the determination of conjunctions and oppositions, including lists of mean and true syzygies beginning in 1321, and associated with a canon beginning Patefit ex Ptolomei disciplines in libro suo. . . . The tables have only been partially analysed.4(4) The Tabulae permanentes, in collaboration with Firmin of Beauval. This is a short text consisting of only one table, a double argument table using signs of 30°, for finding the time interval from mean to true syzygy and a canon explaining its use, beginning Omnius utruisque sexus armonium cele stem....5We have now found another short work by John of Murs in Brussels, Bibliotheque royale, MS 1086-1 1 15, of which, as far as we know, this is the only extant copy.6 It consists of a calendar giving the daily positions of the Sun for 1321 (ff. 24r-25v), a brief canon dealing with a set of tables (f. 26r-v) and the tables themselves, complementing the information given in the calendar (ff. 27r-31r). The first lines of the canon are an enthusiastic comment on the Alfonsine Tables:Notum sit omnibus astronomis presentibus etfuturis quod ex vertiate tabularum alfoncii principis illustris regis castelle que sunt inter ceteras de planetarum motibus veriores, cum per eclipses et coniuncciones sensibiles experiencia probet eas. (f. 26r: 1-3)Let it be known to all present and future astronomers that as far as truth is concerned the tables by the illustrious prince Alfonso, King of Castile, are the most precise among those that address planetary motions, when checked against experience by means of visible eclipses and conjunctions.This text mentions 1321 several times as the epoch of the calendar and it is unequivocally dated 1321 for, at the end of the canons (f. 26v: 13-14), we are told: Finit canon datus anno Domini Ihesu Christi 1321 (Here ends the canon written in the year 1321 of our Lord Jesus Christ).7 It is generally true that calendars for a given year are produced shortly before that year for, in most cases, the information in them would have to be modified to apply to any subsequent year. Thus, this text probably predates all those listed above, with the possible exception of the Expositio, which may have been written at about the same time. It is noteworthy that John of Murs underlines the precision of the Castilian Alfonsine Tables "when checked against experience", a task that certainly takes time. As noted above, in the Expositio John of Murs also indicates his dependence on the astronomical tables associated with Alfonso X of Castile (d. 1284). John of Murs then adds:Ob reverenciam etiam et honorent viri venerabais et solennis in lege fidelium de ordine beati Francisa cuius nomen scribitur in hac arte, normannie partibus oriundi, ego Iohannes sibi compatriota commorans in domo pauperum scholarium de Sorbona hoc opusculum satis breve kalendarium solis et lune nuncupatum extrahere laboravi, per quod sciuntur faciliter conclusiones que sunt in hoc opere, (f. …