EASTER SUNDAY AND THE DOMINICAL LETTER. II 



that is to say, whatever date be taken. For example, year o, 

 by which is meant the year preceding the year One. (There 

 is no year o in chronology. ) To nothing add one-quarter of 

 nothing, which is nothing. Contains seven no times and 

 nothing over. Back nothing from C and get C for the letter of 

 the year o. 



Again, the year One. To one add a quarter of one in 

 whole numbers. This is a contradiction of terms according to 

 our Arabic system of notation. There is nothing to add to 

 one, and one contains seven no times and one over. Back one 

 from C and reach B. 



And so of other cases. 



This method of proceeding would be good from the 3'ear 

 One to the end of time but for irregularities. In 1582 the 

 Julian Calendar was conected by Pope Gregory XIII. Ten 

 days were dropped. Friday, 5th October, was called Friday, 

 15th October. By the rule C was the Dominical Letter. But 

 the change carried F'riday, and in like manner of course, 

 Sunday, forward ten letters, once round the cycle and three over. 



Frida}^ landed upon A and Sunday upon C. 



This three must be provided for in the computation. 



Moreover, as previously remarked, we start from C. We 

 wish to start from G. This gives us another three to be pro- 

 vided for. 



Furthermore, three leap years in four hundred years were 

 suppressed in order to correct the over-correction of leap year. 



There are various ways of dealing with these irregularities. 

 Two will be given, entirely independent each of the other, and 

 models, both, of elegant ingenuity. 



It will be noticed that 1600, the year before the beginning 

 of a new centuiy, has A for its Post Intercalary Letter. Accord- 

 ingly a method of computation has been devised, starting with 

 A, instead of from G, and covering as will be seen the Grego- 

 rian Era, which began in 1582. 



In the prefatory part of the Protestant Episcopal Prayer 

 Book a little Table will be found like this : 



