¤ Perpetual calendar. Oval lithograph printed in green showing the date-numbers within decorative border, mounted on paper, with two movable paper strips w. letterpress days of the week/ months of the year slid through 2x2 incisions left of/ above the date numbers, the oval measuring 6,7x4,7 cm., manufactured prob. 2nd half 19th cent. = By moving the paper strips up or down, any desired correspondance month-date can be established. This way, the calendar can be used, indeed, perpetually.