The Tabor Boy's compass is a beauty, the largest spherical dome compass made by the Danforth Co., with an 8-inch radius. It is housed in a solid brass base with bronze brackets extending from either side, each holding up two 4 1/2-inch iron balls known as quadrantal spheres, which help stabilize the magnetic field. The compass's thick glass has a slight oil coating on the inside for ultraviolet protection, and it lends the glass a smoky look.