THE DETERMINATION OP EASTER DAY. 



157 



scheme of assigning the spring equinox to March 11, instead of 

 dropping ten days of the year. But the idea that the spring 

 equinox had been assigned to March 21 by a Church Council was 

 too firmly rooted in men's minds to be disregarded, and the 

 opportunity of effecting a simple and natural reformation of the 

 calendar was lost for ever. That great astronomer, the late 

 Professor Xewcomb, boldly asserted that, in his opinion, the 

 so-called reformation of the calendar was a mistake ; that it 

 would have been far better to have adhered to the Julian style 

 rather than that people should be worried by the inconvenience 

 caused by the break of continuity. His view was that the 

 change of the seasons relatively to the civil date, consequent on 

 adherence to the old style, would progress so slowly as not to 

 cause any practical inconvenience to the general public. 



It is worth noting that our calendar does not rigidly fix the 

 actual spring equinox to March 21 ; there is an oscillation back- 

 wards and forwards extending over two days. At the present 

 time the equinox frequently occurs on March 20. 



The next point to engage our attention is the determination 

 of the day of the week corresponding to a given day of the civil 

 month in a given year. To find Easter Day we must know 

 what days of the year are Sundays. This is accomplished by 

 means of the Dominical Letters, the use of which, as adopted in 

 the Prayer Book calendar, we must now consider. 



The Dominical, or Sunday, Letters are the first seven letters 

 of the alphabet attached to the several days of the year : A to 

 January 1, B to January 2, C to January 3, and so on, over and 

 over again, throughout the year. No letter is attached to 

 February 29, the intercalary day in the English Ecclesiastical 

 and Civil Calendar. To find the Sundays throughout the year 

 (for a common year) it is then only necessary to note what letter 

 is attached to the first Sunday in the year, and every day 

 throughout the year to which that letter is attached is a Sunday, 

 and the letter is called the Dominical, or Sunday, Letter for the 

 year. Thus January 3, 1915, was a Sunday, therefore C is the 

 Sunday Letter for 1915, and every day in the year to which the 

 letter C is attached in the calendar is a Sunday. In leap years 

 the same letter (D) applies to February 29 and to March 1, so 

 that after February 29 the Sunday Letter for the year retro- 

 grades one place. There are thus two Sunday Letters in a leap 

 year : one from the beginning of the year up to February 29, 

 and the other for the remainder of the year. For example, in 

 1916 the Sunday Letters are B A. As a common year consists 

 of 52 weeks plus one day, and a leap year of 52 weeks plus two 



