Another cylindrical rule is the Thacher Cylindrical Slide Rule. It's a cylinder with many rules marked out on it, that rotates in a set of fixed rules. All to

Another cylindrical rule is the Thacher Cylindrical Slide Rule. It's a cylinder with many rules marked out on it, that rotates in a set of fixed rules. All told it is the equivalent of a 66 foot long conventional slide rule. https://www2.humboldt.edu/scimus/NorthCoastInst/ThacherCalculator/ThacherCalc.htm https://www2.humboldt.edu/scimus/NorthCoastInst/ThacherCalcu... I actually picked one up out of the garbage bin at the university I worked at. It didn't have an inventory sticker so they had to toss it according to the rules.