Remarks upon the solar and the lunar years, the cycle of 19 years, commonly called the golden number, the epact, and a method of finding the time of Easter, as it is now observed in most parts of Europe

Presented as part of a 1750 correspondence between the Earl of Macclesfield and the president of the Royal Society, this treatise surveys the relationship between the solar and lunar cycles that underpins the modern calendar. It begins by comparing the tropical solar year with the older Julian year, showing how a discrepancy of just over eleven minutes accumulates into a full day’s drift over centuries. The author then explains the Gregorian solution—dropping three leap days every four hundred years and retaining the extra day in centuries divisible by four.

In the second section the work turns to the practical side of the calendar: the 19‑year Metonic cycle, the so‑called golden number, and the epact that links lunar months to the solar year. Detailed tables let the reader locate the Paschal full moon for any year from 1583 to 4199 and determine the following Sunday that marks Easter. Listeners will gain a clear picture of how astronomers and church officials historically synchronized seasons, festivals, and the passage of time.