COMMON THINGS THE ALMANACK. 



I like manner it may be shown that the Sunday letter of the 

 next, being a common year, will be F, and in fine, in general, the 

 Sunday letter of a year which succeeds a common year will be the 

 letter which precedes the Sunday letter of the year before. 



The same will be true when a leap year is succeeded by a 

 common year, only in that case the Sunday letter of the latter 

 will be that which precedes the Sunday letter of that part of the 

 leap year which follows the 29th February. 



These observations will be illustrated by the following table of 

 Sunday letters of the years 1840 to 1860 : 



46. It is known to every one that different nations count their 

 years and refer their historical events to different epochs, or ERAS,* 

 as the points of departure have been called. 



47. As may be easily conceived, much confusion arises from 

 this cause. To compare together historical dates which refer to 

 different eras, it is necessary to make a calculation based upon 

 the interval between the eras to which the dates are severally 

 related. It has therefore been considered to be a matter of great 

 convenience to historical students in general to have some fixed 

 era of common reference, to which dates referred to other eras 

 may be reduced, so as to form a common standard of historical 

 and chronological time, as the first day of the year does in the 

 case of civil time applied to shorter intervals. A period has been 

 accordingly agreed upon for this purpose, derived from the com- 

 bination of the three cycles, the Metonic, the Solar, and the In- 



* Etymologists differ as to the origin of this word. The Latin cera is by 

 some derived from the plural of as, brass or money ; in the plural signifying 

 also counters. Others derive it from the Greek ; others from the Arabic ; 

 and according to others, it is composed merely from the initials of the Latin 

 sentence Ab exordia regni Auyusti, "from the beginning of the reign of 

 Augustus." 

 24 



