French perpetual calendar with original description c. 1877

Description“Graphic Guide to the March of Different Circles in the Perpetual CalendarInitial of March – In order for all the days of the moving Circle of days to correspond to the dates of the fixed Circle, one must make adjustments. To find this initial, it is sufficient to identify when March 1st falls on a specific day (e.g., 1877) – Saturday in the entire circle of March 1800, place a Saturday from the moving Circle of days opposite the March 1st of the fixed Circle of dates that corresponds to the 0 of the fixed circle of years; look on this last Circle for the year ’77’ and the day that corresponds to that year; we find ‘Thursday’ = Thursday and thus the initial of March 1877.Wednesday in (1600) (2000) – Monday in (1700) (2100) – Saturday in (1800) (2200) – Thursday in (1900) (2300)Initial of January – Making Thursday correspond to March 1st, it is observed that the day corresponding to January 1st is ‘Monday’ – (If the year is a leap year, the 1st day of the year would be the one that would correspond to December 31st, and the month of February on the fixed Circle of dates would only have 2 days.)Thus, Monday is the initial of January 1877. – but to ensure that the moving Circle of days is accurate for the proposed year, one must determine the date of Easter.Easter – Easter always falls on the Sunday after the full moon that immediately follows March 20th, so it is necessary to establish the position of the large Circle of Lunar Phases. To do this, add 1 to the year of preference. For example: 1877 1 = 18781878 / 19168 / 98 – = Completed CyclesThe remainder 16 will be the golden number 16 = golden number.Place the new moon of the 1st lunar phase of the large Circle of Lunar Phases (indicated by the small bead to rotate the Circle) opposite mark 16 (obtained golden number) of the Circle of Cycles. In this position, observe which day of the lunar phases corresponds to January 1st – we find that January 1st falls between the 16th and the 17th day of the moon. Move along the Circle of Lunar Phases so that it aligns. This same day but of the 1st lunar phase corresponds with January 1st, and thus for the entire year, the corresponding phases.Next, search for the full moon that immediately follows March 20th. The Sunday after this full moon will be Easter. It is found that the full moon falls on March 30th – and that the first Sunday after March 30th falls on April 1st.Align the mark indicating Easter with April 1st in this configuration, all the moving circles and days of the year will correspond with the dates.Passage through the meridian – To determine the time of passage through the meridian or the time of passage through the meridian given the tide time on a given day, match the bead of said Circle of Phases with the bead of the small Circle of Hours on the given day. Note which day of the lunar phase corresponds to the given date; position the large hand on the division of the small Circle of Phases that indicates this same day and align it with the small Circle of Hours, which will indicate the time of the moon’s passage through the meridian.Tides – Adding the indicated time (3h. 31m) to the time of establishment for the tide at La Rochelle, you will have the tide time for the given day.Seen from below the horizon – Observing the position of the moon relative to an observer’s eye at a given time. Position the hand of the moon where it should be seen and note the time. Place the tide hand on the given time, taking into account that the Earth rotates in the opposite direction to the inverse hours on the circle, and it is noon when the tip of the hand is directed towards the division of the given day.Once the hand is positioned at the given time, the observer, standing where the hand and the moon intersect, will see whether the moon is above or below the horizon. The horizon is the perpendicular line to the Earth’s hand and is elevated to the point of intersection of that hand with the Earth.Rise or Set – The time of the moon’s rising and setting will be indicated by the hand at the moment when it is perpendicular to the hand pointing to the moon.Phases of the moon – The hand of the moon, placed where it should be on the day corresponding to the given date, positions its white disk in the direction of the given day so that the perpendicular aligns with the declination line of the 2 points, parallel to the line passing from the given day to the center of the Earth, and then placing the hand of the Earth in the direction of the moon’s circle, will indicate the observer, placed at the birth of this hand, what phase the moon is in. Page 2.Motion of the moon – Like the Sun, the moon has its own motion directed in a known direction compared to the Sun. When a certain day passes through the meridian at the same time as the moon, the moon will be 50′, 28” behind the sun. Depending on its position in relation to the sun, the moon appears in different aspects than the sun. Depending on its position in relation to the sun, the moon appears in different aspects which are called phases. Always showing the same face in the same hemisphere that it … faces during its revolution around …Cycle of a lunar phase – The revolution of the Moon takes 29 days, 12 hours, 44 minutes, 25 seconds. The 2nd mobile Circle intersects the center, representing the tropical revolution of the Moon. It is then divided into 29 days ½ =Cycle of lunar phases – In a tropical year, there are 12.3623 lunar phases. The 3rd mobile circle, starting from the center, represents the annual lunar phase revolution and gives us 12.3683 lunar phases. After a period of 19 years, a period known as the Lunar Cycle with 235 average lunar phases elapses.Lunar Phase Cycle – After a period of 19 years, a period called the Lunar Cycle with 235 average lunar phases elapses. During this time, the same phases reoccur on the same days as during the previous period.Golden Number – The Golden Number refers to the years of the Lunar Cycle. To determine the Golden Number of a year, recall that the 1st year of the Lunar Cycle is preceded by an order of the year… the following cycle. Example: For the year 1877. Add 1 year 187 or 1878/19 = 1878/19Epact Abareher of the grand Circle of Lunar Phases. 1968/98 = 16The remainder 16 means that the year is the 16th year of the 99th Cycle = this remainder 16 is therefore the golden number of this year.Epact – Epact is the number of days elapsed since the last lunar phase of the year or the beginning of the following year.the grand Circle of Lunar Phases – In 12.3683 lunar phases, the number 3683 represents the epact. Assuming that January 1st of a previous year = then if we have 2 concentric circles, one representing the days of the year and the other the 12.3683 lunar phases, and the New moon of the 1st lunar phase corresponds with January 1st of the fine circle, the following year move the mobile circle back by 3683 from one lunar phase and you’ll have the corresponding lunar phase.Corresponding to January 1st of that year. If in this position, you again circle the same distance from the mobile circle, you’ll have again the corresponding phase for the 1st day of the 3rd year = repeat this process every year from this same distance, and after 19 years, this circle will indicate on January 1st the same phase as this same circle indicated on January 1st of the previous 19th year. If a 3rd concentric fixed circle to these 2 circles indicates this distance of 3683 repeated 19 times, each division represents the golden number of the year.For a given year, place the New moon of the 1st lunar phase of the Circle of Lunar Phases opposite the lunar phase in such a way that the 17th day of the 1st lunar phase corresponds with January 1st, and you will have all year round the corresponding phases.Example = For the year 1877 with a golden number of 16. Place the New moon of the 1st lunar phase of the Circle of Lunar Phases opposite the lunar phase in such a way that the 17th day of the 1st lunar phase corresponds with January 1st, and all year you will have the corresponding phases.”