Sixtus IV became pope early in August, 1471, Nicolò Tron was elected doge on November 23d of the same year, and died in July, 1473. We can thus date the book as “about 1472” with absolute confidence. Writers of poetical colophons are naturally more inclined to use regnal dates than the year of the Lord, which it is seldom easy to get into a verse. In the “Moral Prouerbes of Cristyne” Caxton gives us the month, the day, and the regnal year, together making a precise date. This colophon runs: Of these sayynges Cristyne was the aucturesse, Whiche in makyn[g] hadde suche intelligence, That thereof she was mireur and maistresse; Hire werkes testifie thexperience; In Frenssh languaige was writen this sentence, And thus englished doth hit reherse Antoin Wideuylle, therle Ryuers. Go thou litil quayer and recommaund me Unto the good grace of my special lorde Therle Ryueris, for I haue emprinted the At his commandement, following eury worde His copye, as his secretarie can recorde, At Westmestre, of Feuerer the xx daye And of Kyng Edward the xvij yere veraye. Emprinted by Caxton In Feuerer the colde season. The seventeenth year of Edward IV ran from 4th March, 1477, to 3d March, 1478, so that the “Moral Proverbs” were finished on February 20th of the latter year. When a change of sovereigns occurred in the year in which a book was printed, the mere name of the earlier or the later of the two shows in which part of the year the colophon was written, and regnal dates supply the same information for years in which no change of sovereigns took place. Thus the colophon to Wynkyn de Worde’s edition of the “Vitas Patrum” ends: “Enprynted in the sayd towne of Westmynstre by me Wynken de Worde, the yere of our lorde M.cccc.lxxxxv. and the tenthe yere of our souerayne lorde Kyng Henry the seuenth.” As Henry VII’s reign began 22d August, 1485, its tenth year would cover the twelvemonth, August, 1494, to August, 1495, and we are thus told not only that the book was issued in 1495, but that it was printed before August 21st of that year. A subsidiary date, of course, as a rule loses its usefulness when the printer explicitly mentions also the month and day on which the book was completed. It may, however, have a special value as furnishing a means of fixing the day from which the printer reckoned his year. In the fifteenth century the year could be reckoned as beginning on Christmas day, on January 1st, on March 1st, on March 25th, or at Easter. In arranging the books issued from any press in chronological order, it is of vital importance to know which reckoning the printer followed, and we may now give some examples to show how regnal years can be used to settle this.