Perpetual calendar with sleeve and sliding cursor has tables of dates on sleeve to be aligned with names of days and months on cursor

摘要

The calendar consists of a sleeve (1) with windows (7a, 7b) and a sliding cursor (2) printed with the names of the months (8a) and days of the week to be aligned with the windows. The sleeve is printed with tables (4) of the years of a century in 18 columns of six figures in 126 boxes, together with tables according the first year of each century a letter between A and G, and another table (10) of the dates in a month in columns A - G. By aligning the first Sunday in a year with the appropriate date on the sleeve any date of any year can be read off.