Fabulous C. 1820s Century Mechanical Ink and Watercolor Perpetual Almanack, Ready to Use

So cool, and so crisp and modern feeling, though about 200 years old! It is a working perpetual calendar, ink and watercolor on card, with a tab on the back side that moves up and down to change the day of the week, making it ever applicable. With the days of the month arranged in a neat grid at center, and the hand-written text on the column at right noting the number of days in each month. ("Feb. hath 28 or 29 days") A bit akin to a mechanical valentine, but also very reflective of the 18th and early 19th century obsession with "perpetual almanacks" of which there are some extraordinary (and very very precious) examples. Here's an engraved one structured in a similar manner to this one, c. 1820. 

5 3/8" x 4 4/5". Beautiful working condition, watercolor and ink bright and crisp and bold. Just a minor stain/toning to bottom left of left column.  On card.