I was sold on these just by the lovely paper sleeve encasing them, with a heart hand-inked by the Ruth who once owned them to boot. They are a set of drawing cards, produced for use in schools, specifically "Coe’s New Drawing Lessons No 1." printed by D. Appleton & Co., New York, 1858, and described here as "A Method by which all the Members of a Large Class are taught to Draw at Once with Neatness, Uniformity, and Accuracy." (And indeed, it you've spent time looking at sketchbooks from the third quarter of the 19th century, some of these images will look very familiar!) 

Inside are nine cards of what was once a larger set, described on the cover as divided onto four groups: No. 1. Perpendicular and Horizontal Lines; No. 2. Oblique and Curved Lines; No. 3. Curved Lines and Introduction to Landscape; and No. 4. Studies in Landscape. (Of these nine, only groups 1 & 2 are represented here, as indicated by roman numerals at upper left--a nice selection of architectural structures though.) These are scarce--the only other sets I've found as reference are in museum collections, with the Huntington the best reference for this particular set (link here). 

Sleeve measures 5 5/8" x 4 7/16". Nine cards included. General scattered toning/foxing to the cards. Sleeve shows general wear but is holding together  well and is very lovely, with blue ink stamped pattern visible along edges and back.