it's in the details - deconstructing the patented o.c. white knuckle joint

this diminutive early american industrial iron and steel contraption - identified simply as an "adjustable supporter" or knuckle joint, was patented by otis c. white (a dental surgeon from hopkinton, massachusetts) in 1893 for use with electric lamps or lighting, that over time, would gain widespread use in factory and/or various commercial settings throughout the country. the "lamp supporter" or compound swiveling, sliding and clamping joint, was designed in part to connect primary and secondary tubular steel arms of an articulating lamp or light fixture. in addition, the joint provided longitudinal and rotative adjustment of the secondary arm in all directions relative to the primary arm. the brushed cast iron and steel joint (as shown above), consists of a swiveling head having an adjustable grip and clamping jaw for securing the lamp arms (i.e., primary and secondary). the swiveling head is fitted to rotate on the seat located on the main part of the joint, and is axially retained by a pivot or threaded screw that passes through the aforementioned parts. the pivot includes a circular head located in a cavity within the swiveling head. the pivot is non-rotatable in the main part of the joint, and a nut or binder (i.e., "faucet" handle) is fitted on its opposite end outside the clamp jaw, so that by tightening the nut, the multiple parts can be clamped together with sufficient friction for retaining the lamp's arms at any desired angular position. a yielding washer is typically utilized between the nut and jaw to render the action more efficient than rigidly clamping the parts together. a small, threaded and knurled set-screw or dial is employed for adjusting the pressure of grip on the adjustable arm containing the light source (e.g., incandescent lamp socket with or without reflector). this remarkable device, that has gained such widespread popularity for its usability, functionality and elegantly simple design has no doubt proven the test of time. such a wonderful novelty to marvel at in the palm of your hand...