Perpetual calendars

Abstract

Abstract A PERPETUAL CALENDAR IS DESCRIBED WHICH MAY BE IN THE FORM OF A SLIDE RULE, FOR EXAMPLE, IN WHICH TWO MEMBERS ARE RELATIVELY MOVEABLE. ONE CARRIES INDEXING POSITIONS, ONE FOR EACH DAY OF THE WEEK, AND THE OTHER CARRIES AN INDICATOR, ARRANGED IN NUMERICAL SEQUENCE, OF THE YEARS OF A CENTURY. THE INDEXING POSITIONS ARE ALLOCATED TO CENTURIES (ACCORDING TO THE JULIAN AND GREGORIAN CENTURIES) BY REFERENCE TO THE WEEK-DAYS ON WHICH THEY TERMINATE, AND THE SPACING BETWEEN THE POSITIONS IS DETERMINED ACCORDING TO UNIT LENGTH MULTIPLES, IN WHICH A UNIT LENGTH IS GIVEN A SINGLE-DAY SIGNIFICANCE AND THE PITCH OF THE POSITIONS IN A MULTIPLE OF SEVEN UNIT SPACES, PLUS ONE UNIT. THE YEAR INDICATOR IS ALSO SPACED OUT, EACH COMMON YEAR INDICATION BEING SPACED BY ONE UNIT FROM ITS PREDECESSOR IN TIME AND EACH LEAP YEAB BEING SPACED BY TWO UNITS. THUS THE RELATIVE MOVEMENT OF THE TWO MEMBERS TO ASSOCIATE A REQUIRED YEAR WITH A REQUIRED CENTURY POSITION INDICATES THE TERMINAL WEEK-DAY OF THE REQUIRED YEAR. A CALENDAR ON ONE MEMBER WITH THE DAY ALLOCATIONS OMITTED MAY THEN BE COMPLETED BY THE ASSIGNMENT OF DAYS FROM A REPETITIVE "DAY"-STRIP ON THE OITHER MEMBER. THE TERMINAL DAY INDICATIONS MAY, BY PREDETERMINED ASSOCIATION WITH CODE LETTERS, BE MODIFIED TO SHOW THE DOMINICAL LETTER FOR THE CALCULATION OF EASTER DAY IN REESPECT OF THE REQUIRED YEAR. A COMPOSITE PERPETUAL CALENDAR AND EASTER CALENDAR DEVICE MAY BE FORMED BY PRO- VIDING A FURTHER ASSOCIATION OF INDEX POINTS AND INDICATIONS. TAKING INTO ACCOUNT EPACT AND GOLDEN NUMBER CYCLES, THE YEARS OF A CENTURY MAY BE INDICATED AT A REGULAR SPACING, AND CENTURY INDEX POSITIONS PROVIDED SO THAT THE RELATIVE MOVEMENT OF THE TWO MEMBERS TO ASSOCIATE A REQUIRED YEAR WITH A REQUIRED CENTURY WILL SELECT A GROUP OF SEVEN DATES ON WHICH EASTER DAY MIGHT FALL IN THE REQUIRED YUEAR, AND REFERENCE TO THE DOMINICAL LETTER THEN ENABLES THE PARTICULAR DATE FOR EASTER DAY TO BE SELECTED. THE EMPACT AND GOLDEN NUMBER FOR THE REQUIRED YEAR MAY ALSO BE DISPLAYED.

Inventors

• 👤 Albert Alexander Dickson

Bibliographic Details