Soon after the publication of the former edition of this work, it was suggested that a chapter be added on Easter; rules for fixing its date, and also church festivals that depended upon the date of Easter. It was suggested that this would add very much to the value of the work, if so presented as to be brought within the comprehension of ordinary minds. Knowing that the determination of Easter was an affair of considerable nicety and complication, and had had the attention of our best minds, and they had failed so to present it, that even among scholarly men, probably not one in a hundred was able to determine its date without referring to tables prepared for that purpose the author of this work felt as though he was hardly competent for the task. Nevertheless it was undertaken, and the work has been revised and enlarged by a Chapter on the Peculiarities of the Roman Calendar, another on fixing the date of events prior to the Christian era, and a third part on Easter, church festivals, and the Hebrew Calendar. In the opinion of the author, the rules for determining the date of Easter are so simplified by his new method that any person of ordinary intelligence may understand them. How well he has succeeded the public will decide. G. N. P. CONTENTS. PART FIRST. DEFINITIONS--HISTORY. _Pages._ CHAPTER I.--Definitions 11 CHAPTER II.--History of the divisions of time, and the old Roman Calendar 12 CHAPTER III--History of the reformation of the Calendar by Julius Caesar 18 CHAPTER IV.--History of the reformation of the Julian Calendar by Pope Gregory XIII 20 CHAPTER V.--Peculiarities of the Roman Calendar 26 PART SECOND. MATHEMATICAL. CHAPTER I.--Errors of the Julian Calendar 36 CHAPTER II.--Errors of the Gregorian Calendar 38 CHAPTER III.--Dominical Letter 39 CHAPTER IV.--Rule for finding the Dominical Letter 44 CHAPTER V.--Rule for finding the day of the week of any given date, for both Old and New Styles 50 CHAPTER VI.--A simple method of finding the day of the week of events, which occur quadrennially; the inaugural of the Presidents, the day of the week on which they have occurred and on which they will occur for the next one hundred years 61 Some peculiarities concerning events which fall on the 29th of February 64