While this wire rope caliper rule is not marked by maker, it was almost surely made by Kerby & Bro. of New York. The rule is marked for the John A. Roebling’s Sons Co. of Trenton, N.J.. One side shows a table for standard hoisting wire rope, giving the weight of the rope per foot, its breaking strength in tons of iron, and breaking load in tons of cast steel. The other side provides the minimum size of drum and sheave in feet for diameters from3/” to 3 ¼ inches. The slide caliper measures both the diameter and circumference of the cable. Fine.