Wooden school abacus 30s

Large wooden abacus from the 30s. A rare piece that was sometimes found in schools at the beginning of the 20th century. Superb pigeon blue patina, very decorative. Missing a ball line at the very bottom so not troublesome and a ball on the penultimate line. So nice in a child's room. H 179 / l 74, 5 / p 35, 5 cm.