Under 17, In Line B, The Epact Is 25'.
Another Addition Of Eleven Gives Thirty Three For The Epact Of The Fourth Year; But In Consequence Of The Insertion Of The Intercalary Month In Each Third Year Of The Lunar Cycle, This Epact Is Reduced To Three.
But the fourteenth of this moon falls at the latest on the 18th of April, or 29 days after the 20th of March; for by reason of the double epact that occurs at the 4th and 5th of April, this lunation has only 29 days.
Hence We Derive The Following Rule For Finding Easter Sunday From The Tables: 1St, Find The Golden Number, And, From Table Iii., The Epact Of The Proposed Year.
The Epact 19' (Also Distinguished By An Accent Or Different Character) Is Placed Table Iii.
The Reason Of This Is, That The Intercalary Month, Inserted At The End Of The Cycle, Contains Only Twenty Nine Days Instead Of Thirty; Whence, After 11 Has Been Added To The Epact Of The Year Corresponding To The Golden Number 19, We Must Reject Twenty Nine Instead Of Thirty, In Order To Have The Epact Of The Succeeding Year; Or, Which Comes To The Same Thing, We Must Add Twelve To The Epact Of The Last Year Of The Cycle, And Then Reject Thirty As Before.
The Epact Of The Following Year Is Therefore Twenty Nine.
It Is, However, Only Used In Those Years In Which The Epact 19 Concurs With The Golden Number 19.
Line C) is 26.2nd, 19 r After the 7th of March the epact 26 first occurs in Table III.
In Consequence Of The Solar And Lunar Equations, It Is Evident That The Epact Or Moon'S Age At The Beginning Of The Year, Must, In The Course Of Centuries, Have All Different Values From One To Thirty Inclusive, Corresponding To The Days In A Full Lunar Month.