Dip circle consists of a brass cylinder with two glass flat end-windows, containing a centrally mounted magnetic needle free to rotate about its supporting axis in a vertical plane. The needle , when at rest is arrested by a trunnion from which the needle can be raised by means of external knob. Very close to the needle is mounted the vertical circular scale. Two magnifiers are mounted at the end of a brass “diameter’ which can be rotated so as to read off the angular positions of both ends of the needle after being set up. Graduated horizontal scale on the base. Spirit level mounted. Tribach base.Engraved on base: “Robinson 38 Devonshire Street Portland Place London”