CHRONOLOGY. - The study of historical sources (chronicles and documents) requires the historian and the diplomatist to check the date offered by the document or the chronicle, with the twofold purpose of ascertaining the authenticity of the dating and of translating it into modern style (v. ANNO; ERA). If, for example, a document bears the date 1281, it may, after the appropriate verifications, turn out instead to be from 1280 or 1282, according as the style ab Incarnatione was used in the Pisan or the Florentine manner. Likewise, one must calculate whether the indiction (v.) is correct and corresponds to the year, according as the Constantinopolitan or the Bedan indiction is employed.
The dating by day, month and year in use today was not always and everywhere employed. Sometimes, for example, instead of the day and the month, it was customary to give the name of a saint, the recurrence of a market, Easter Sunday, etc.; it may moreover happen that some document indicates, with apparent scrupulousness for exactness, even the day of the week. In that case, one must ascertain whether in that year the indicated day of the week really coincided with the day of the month that accompanies it: where it does not, the discrepancy may constitute an indication of falsity. Elsewhere, instead of the year according to the Christian era, we may find the years of a sovereign's reign. Here too one must verify to which year, according to modern reckoning, the document belongs and whether that sovereign really reigned in that year, and so on.
To all questions of this kind the c., or art of verifying dates, responds.
It is divided into two branches: the first, technical (chronography), which studies the use of the various types of calendar, of the various eras, of the various styles, of chronological computations for the determination of movable feasts, and provides the elements suitable for translating into modern style the chronological notation given by the document; the second, historical (chronistory), which provides lists of persons or of events, in strict order of time.
Already in the Middle Ages great importance was given to c., also for practical and religious reasons (v. COMPUTO ECCLESIASTICO); it suffices to recall the De temporibus and the De temporum ratione of the Venerable Bede. In modern times c. developed in step with diplomatics. The first essays were the Opus de emendatione temporum of Scaliger (Paris 1583) and the Opus de doctrina temporum of Petau (ibid. 1633). But the greatest treatise is the Art de vérifier les dates of the Benedictines M. d'Antine, C. Clémencet and O. Durand, published in 1st ed. in Paris in 1750 and then revised and republished several times up to 1844. More modern are the works of L. de Mas-Latrie, Dictionnaire de statistique religieuse (Paris 1851) and Trésor de chronologie (ibid. 1899). Among the expositions of technical c. one is to be remembered, for clarity and perspicuity, that of A. Giry (Manuel de diplomatique, ibid. 1894). In Germany the works of H. Grotefend are remembered (especially practical are the Handbuch der historischen Chronologie, Hannover 1872, and the Taschenbuch der Zeitrechnung des deutschen Mittelalters und der Neuzeit, 6th ed., ibid. 1928) and those of E. Brinckmeier. Among the modern manuals are remembered: F. K. Ginzel, Handbuch der mathematischen und technischen Chronologie (3 vols., Leipzig 1906-14); A. Cappelli, C., cronografia e calendario perpetuo (2nd ed., Milan 1930).
Carmelo Trasselli