W.J. Sidis Archives       Photo of Calendar     Geprodis Org. News, No.7       Print Your Own

        This application is a division of my application No. 240,214, filed December 15, 1927, Patent No. 1,718,314, June 25, 1929.

        The invention relates to perpetual calendars in which week-days can be found directly for any given date whatever; and its object is, first, to provide a means by which all such week-days can be looked up in a direct, simple and easily understandable manner; secondly, to avoid the cross-reference tables or complex mechanism, one or the other of which have hitherto generally been features of perpetual calendars providing means to look up the week-day of any given date whatever; thirdly, to provide a perpetual calendar which, once the calendar is adjusted for any given year, a complete and condensed calendar for the year is at once plainly visible; fourthly, to simplify the parts and their interrelation by the elimination of indicators or pointers which add both to the difficulty and expense of manufacture and to the derangement of the operation of the calendar.

        The invention is illustrated in the two figures of the accompanying drawing, the front sheet or card being represented in Fig. 1, and the disk forming the remainder of the calendar being represented in Fig. 2.

        The essential features of the calendar are a front sheet or card (see Fig. 1), and a disk (see Fig. 2), these two parts being attached to one another by means of a pivot or other rotating device whereby the disk may be made to rotate freely about a suitable fixed point of the front sheet.

        The said disk consists of two concentric sections, the center being the pivot or axis about which the disk rotates; these two sections are the month-section (1) and the year-section (2).

        The month-section consists of twenty-four or more sectors, each containing the name of a month or a set of such names. At least thirteen of such sectors shall contain the names of months arranged in the cyclical order of the week-days on which they begin in leap-years; and at least thirteen of such sectors shall contain the names of months arranged in the cyclical order of the week-days on which they begin in non-leap-years; when several months in a leap-year, in a non-leap-year, as the case may be, begin on the same week-day, all such months are in the same sector.

        The year-section (2) shall consist of a group of leap-years (3) in seven sectors, and a group of non-leap-years (4) in seven sectors, the sectors comprising each the same angle about the common center of the disk as the month-sectors. These sectors correspond to the month-sectors separated from them by the same angle of the disk's arc that separates the initial edge of the year-slot (5) from that of the month-slot (6).

        All the years within a definite period (in this case 1900 to 1956) are placed in one of the fourteen sectors mentioned in the preceding paragraph such year being placed in the leap-year or non-leap-year sectors according as it is or is not a leap-year; and each year further being placed in the sector corresponding to the months beginning in that year on the week-day (Sunday in the instance illustrated) found in the first row and first column of the week-day group (7) on the front sheet.

        The front sheet (see Fig. 1) of the calendar has two perforations, a month-slot (6) under which the month-section (1) of the disk rotates, and disclosing seven sectors of said month-section; and a year-slot (5) of such shape and size that, when properly adjusted, it discloses just one sector of the year-section (2) of the disk, said sector being that corresponding to the first month-sector visible through the month-slot.

        Upon the front sheet of the calendar also is a group of week-days (7) arranged in seven rows and seven columns so that in each row and in each column the seven days of the week appear in the cyclical order in which they occur, and so that the continuations of the seven rows fit the seven month-sectors visible through the month-slot (6) when the disk is properly adjusted; also a group of date-numbers (8) from 1 to 31, occupying the continuation of the seven week-day columns, the said numbers being listed in succession, row by row.

        In addition, the front sheet of the calendar should contain a conversion-table (9), stating how many years have to be added or subtracted in order to use the calendar for years not listed in the year-section (2) of the disk.

        The pivot (10), or any other similar rotatory device, furnishes a means whereby the disk may be rotated behind the front sheet so that the year desired will appear through the year-slot (the conversion-table being used in the case of years not within the period covered on the disk). When this is done, the months appearing through the month-slot, and the week-days and date-numbers on the front sheet, constitute a complete and condensed calendar for the year in question, the week-day for any date appearing in the same row as the month, and the same column as the date.

        I claim:

        The combination, in a perpetual calendar, of a disk containing the months properly grouped in sectors and the years occupying sectors of the same disk in a concentric ring; a front sheet with two slots making visible respectively the month-sectors and a year-sector, and containing week-days in seven rows and seven columns, and date-numbers occupying a continuation of those seven columns; with a pivot by means of which the disk may be rotated at will with reference to the front sheet.
                                                                                               WILLIAM JAMES SIDIS