THE NEW SCHAFF-HERZOG
in 7S1 by Godesscalc at the command of Charlemagne, a calendar from Luxeuil of the latter part
of the seventh century, a marble
6. Later calendar drawn up at Naples by
Medieval Bishop John IV between 840 and 850,
Calendars, and a calendar of Bishop Gundekar
II. of Eichstatt (1057-79). Among other German calendars mention may be made of one from Freising of the latter part of the tenth century, from Salzburg in the eleventh century, from Regensburg in the twelfth, and from Passau and Augsburg in the thirteenth. Toward the end of the Middle Ages the Latin calendars began to be translated into the vernacular, although a metrical calendar had been written in Anglo-Saxon before the close of the tenth century. A French calendar of the thirteenth century is still extant in manuscript, but German calendars, which are tolerably numerous, are not found until a hundred years later. The invention of printing in the fifteenth century wrought important changes in the calendar, although the first printed specimens resemble those in manuscript and, like them, are perpetual. The first calendar for a definite year was printed at Nuremberg in 1-175 in German and Latin. It was designed for the years 1475, 1494, and 1513 as the first of a triple cycle of nineteen years each, and was so constructed that the dates for other years might be derived from these three, so that it really extended from 1475 to 1531. The ecclesiastical portions, however, were in perpetual form, since the calendar contained, in addition to the letters A-G for the days of the week, only the names of the saints for a limited number of days without a division into weeks and without the movable feasts. It was not until the middle of the sixteenth century that calendars arranged according to the weeks and feasts of a definite year came into general use.
The reckoning of Easter hitherto employed had long been recognized as inadequate, and the elimination of the errors which this system had caused was one of the most urgent tasks which awaited solution after the close of the Middle Ages. Since the second half of the third century the rule had been adopted by the Alexandrian Church, and confirmed by the Council of Nicasa, that Easter should fall on the Sunday after the spring full moon, that is, on the first Sunday after the full moon on or next after the vernal equinox. The date of this
equinox was to be Mar. 21, while the 7. Errors in full moon was to be reckoned accord- Calculating ing to a cycle of nineteen years. This Easter. system of reckoning was introduced
into the Roman Church in 525 by Dionysius Exiguus, and spread thence throughout Italy, Gaul, and Spain, and was given to the Anglo- Saxon churches by Bede in 729. This method, however, was vitiated by two faults which could not fail to become evident in the course of time. In the first place, by its assumption that the vernal equinox falls on Mar. 21 it adopted the entire Julian system which makes the vear 365J days in length and intercalates a day every four years. In reality this year is eleven minutes too long, so that an extra day is intercalated every 128 years. In the second place, by its reckoning of the spring full
moon according to a nineteen-year cycle of 235 months or 6,939f days, it made the cycle an hour too long, thus making a discrepancy of the day between the real and the theoretical new moon every 210 years. It was not until the thirteenth century that this error attracted attention, the first works to note it being the Computus of Master Conrad in 1200 (extant only in a revision of 1396 in a Vienna manuscript) and the similar work of an anonymous author of 1223 (preserved in great part by Vincent of Beauvais). The problem was likewise taken up by Johannes de Sacro-Busto about 1250 in his De anni ratione and by Roger Bacon in a treatise addressed to Clement IV., De reformatione calendarii, while among the Greeks the monk Isaac Argyros wrote on the problem in 1272. In the fifteenth century the reformation of the calendar was discussed in the great councils of the Roman Catholic Church, especially by Pierre d'Ailly at Kostnitz in 1414 and by Nicholas of Cusa at Basel in 1436, the latter proposing to begin the correction of the calendar in 1439.
The actual reform of the calendar was first carried out by Gregory XIII. (1572-85) in conformity with a resolution of the Council of Trent. In 1577 the pope appointed a committee which held its sessions at Rome to carry out the plan proposed by the Calabrian astronomer Aloigi Ligli, and confirmed this reformed calendar, which was called the Gregorian in his honor, by a bull of Feb. 24, 1582. The reform was designed, on 8. The the one hand, to regulate Easter with
Gregorian reference to the solar and lunar revo- Reform. lutions, thus restoring the year of the lunar cycle according to the date and intention of the Nicene Council, and, on the other, to avoid any future shifting of the vernal equinox and the spring full moon. To restore the vernal equinox to Mar. 21, the ten days between Oct. 4 and 15 were dropped, while for the correction of the spring full moon the new moons were set back three days from Jan. 3 to Dec. 31. These corrections were assured by retaining the Julian system of intercalation and the nineteen-year lunar cycle for a century. The intercalary day was to be omitted thrice in four centuries, and the new moon was to be retarded one day eight times in twenty- five centuries (seven times after each three hundred years and the eighth time after four hundred). For the correction of the lunar cycle the reckoning of epacts, or the age of the moon on Jan. 1 , was introduced according to the cycle proposed by Ligli.
The Gregorian calendar was adopted in Roman Catholic countries either immediately or in the course of a few years. The Protestant districts, on the other hand, opposed it, partly on account of their hostility to Rome and partly on account of its chronological discrepancies. Its inaccuracies were recognized by the landgrave
9. Opposi- William IV. of Hessc-Cassel, and the tion to the Calvinistic Joseph Justus Scaliger is-
Gregorian sued repeated warnings against it.
Calendar. After the end of the sixteenth century the Julian calendar existed in Germany side by side with the Gregorian, the two being designated as old and new style, respectively. The