EASTEE. 



firmament, nor does " full " moon mean a moon with a complete 

 circular phase. 



It often happens, accordingly, that the day appointed in the 

 calendar for Easter Sunday is altogether different from the day on 

 which that festival would fall, if the terms of the rule were used 

 in their usual sense, and in such cases we find the newspapers 

 filled with indignant imputations of error in the calendar, and 

 visiting the public wrath upon those under whose direction it was 

 compiled and computed. 



17. We have shown that the commencement of spring, or what 

 is the same, the moment of the spring equinox, is subject to 

 variation in relation to the civil year, falling sometimes on the 

 20th and sometimes on the 21st March. The spring equinox of 

 the calendar is, however, an imaginary equinox, which is 

 supposed never to vary from the 21st March. Thus, even when 

 the real equinox falls on the 20th March, the fictitious equinox of 

 the calendar, by reference to which Easter is determined, still falls 

 upon the 21st March. 



18. The term " moon " in the rule signifies also a fictitious object, 

 created or imagined expressly to suit the purposes of the calendar. 

 Nor is the adoption of such a fiction, where it serves convenient 

 purposes, unwarranted or unusual. Astronomers themselves 

 have found their computations of the celestial phenomena 

 materially facilitated and simplified by creating fictitious suns, 

 moons, and planets, to which imaginary motions are imputed ; and 

 it may, therefore, be fairly contended that the creation of a 

 fictitious moon for ecclesiastical purposes is not less justifiable. 



The ecclesiastical moon is an object whose motions are governed 

 by certain numbers, called the " golden numbers" and the 

 "epacts." These numbers have a relation to the periodical 

 changes of the real moon, in virtue of which the place of the 

 ecclesiastical moon can never vary from that of the real moon 

 beyond a certain limit. Thus the full of the one may differ by as 

 much as two days from the full of the other, but not more. 



A "full" moon, whether real or fictitious, is that which is 

 presented at the middle of the interval between two successive 

 new moons. Thus, if this interval be 29| days, the full moon will 

 take place in 14f times 24 hours after the moment of new moon. 

 Now this is not the sense in which " full" moon is to be under- 

 stood in the rule. To define exactly the sense of " full " moon in 

 the rule, it will be necessary first to explain how the " age" of 

 the moon is expressed in the language of the calendar. 



19. The day upon which the moon is in conjunction with the 

 sun, or, what is the same, upon which new moon takes place, is, 

 properly speaking, shared between the old and the new moons. 



