MEMOIR EXPLANATORI OF A \V.\\ PERPETUAL CALENDAR. 105 



their scrutiny. To them a difference of "methods," technically so called, being, for the 

 most part, of little consequence, my proposal to "free the civil calendar from algebraic 

 formula'," (which are apt to convey, to their minds, the best evidence and guidance,) may 

 at first sound strangely; but the attempt will possibly appear to them, upon retlcction, 

 (piite consonant with the improved spirit of the present age, which brings, whenever prac- 

 ticable, things of common concern and use to common comprehension. In regard to the 

 Church calendar, indeed, which Delambre declares to be " excessivement complique ct qui, 

 pour etre bien compris, exige l'attention la plus soutcnue," 1 must admit it to be doubtful 

 whether in any shape yet assumed, it is likely to become an inviting or fruitful object of 

 inquiry to the generality of persons. 



The next page exhibits, and the succeeding one exemplifies my plan, the constituent 

 parts of which are embodied in a single Tablet or Perpetual Calendar, having its pecu- 

 liarities specified in the title. In addition to the two general Rules, it will be seen to con- 

 sist, principally, of a central column, headed "Eras," which serves as an index to two 

 series of corrections, called (in compliance with customary fictions and nomenclature,) 

 the Solar and Lunisolar Equations. These are comprised in two side columns of equal 

 length with the central one, and accompanying it; column A being appropriated to civil, 

 and column C to ecclesiastical purposes. 



The Julian Era, though employed by astronomers as a convenient universal measure of 

 time, is here limited to years after Christ, but embraces, of course, all those years which 

 precede the adoption of the reformed calendar, at various epochs, by the several nations 

 of Christendom. That is to say, the equations 5 and respectively, standing at the head 

 of the side columns, and "beside" the Era denominated " Julian after Christ," arc in- 

 tended to be used constantly until such a reformation has actually taken place. The Era. 

 denominated "Gregorian from 1582," is divided into ccnturial figures, but the equations 

 standing beside these subdivisions arc not meant to be applied to the interval, for example, 

 of nearly 170 years which occurred between the adoption of the New Style at Rome, and 

 in Great Britain. Without this preliminary caution, the word "Eras," as employed in 

 die tablet, might possibly mislead some readers. 



The asterisks annexed to the ccnturial figures arc not essential to the use of the Tablet, 

 but arc retained for the purpose of better elucidating its structure. Tin 1 intervals between 

 them on the civil side, make known, however, at once, through the eye, those n-ntcsiiini! 

 pears which, in New Style, are not bissextile; and they furnish also a ready means of as- 

 certaining the whole number of days, by which, at any period after L600, the two styles 

 differ from each other. For instance, in years having the ccnturial figures 26, the differ- 

 ence between Old and New Style amounts to 18 days: for 1<) (the number of days origi- 

 nally suppressed,) together with the 8 ccnturial figures which are destitute of asterisks, 

 (viz., 17, 18, 19, 21, 22, •_>:'.. 25 and 2G,) make the sum 18: in like manner, the difference, 

 w ith our present ccnturial figures is 12 days: for 10 + 2 (17 and 18 bciiiL! unmarked)- 12. 



The two auxiliary table- [5 and I) demand no attention until some pro •< hall have 



bcui made in the explanations ofth< general rules, upon which 1 am now to enter. 



