1841. J Scheme of a Table for all Time. 597 



days were added to the reckoning by counting the 14th instead of the 

 4th of October, as it was estimated that so much had been lost during 

 the interval. It would, however, have been correct had only 9 days 

 been added, because from 325 to 1582 there are 1257 years, during 

 which 3 days having been lost every 4 centuries, it is clear that 9 days 

 must have been lost in 1200 years, and the reckoning of the odd 57 

 years being the same according to both styles. 



By adding ten days to the Calendar, the festivals have in fact been 

 adjusted to what they were in the century before the Council of Nice. 



This mistake may be shewn by the Table, where it is seen that the 

 same week-day is common to the full century 30 according to both 

 styles, and as the coincidences occur at intervals of 28 centuries, the 

 same week-day is common to both styles in the full century 2, whereas 

 the week-days of the full century 3 differ in Old and New Style. The 

 agreement would be perfect in the year 225, but wrong by a day 

 in the year 325. 



This mistake in adjusting the New and Old Styles, is similar to that 

 committed in settling the Epoch of the Christian Era, the true time, as 

 is now generally admitted, being 4 years before the common reckoning.* 



As it is often convenient to reckon dates before the Christian Era 

 in Julian years, I have given a rule for finding the week-days of such 

 dates with facility, by observing that they recur in the same order 

 every 700 years. The rule is this : subtract the given year diminished 

 by one from any convenient multiple of 700, and use the remainder as 

 if it were a common Old Style date. 



As the Gregorian adjustment of the Calendar causes an error in 

 excess of about one day in every 40 centuries, this may be allowed for 

 by adjusting the full century-division not to the 00, but one division 

 to the right of it for every 40 centuries. This adjustment renders 

 the Calendar perpetual, so far as depends upon our present knowledge 

 of the length of the year ; but the adoption of this, or the correction of 

 any error which may be found to be involved in it, will remain for 

 future generations. 



22nd March, 1841. 



P.S — The proper method of manipulating the Perpetual Time Tables, 

 is the following : — In adjusting the full century to the zero, put the two 



* See Barlow's Mathematical Dictionary, art. Epoch; or the Essay in Fergusson's 

 Astronomy. 



