The spring-and-lever balancing mechanism, George Carwardine and the Anglepoise lamp

Two short and direct methods of exact analysis of the spring-and-lever bala ncing mechanism are presented. It is shown that perfect balance can be achi eved by the use of a close-coiled spring whose free length is effectively z ero and whose stiffness is chosen appropriately. The two-degree-of-freedom balancing mechanism, commonly seen in desk lamps but useful in many other s ituations, is then analysed. The treatment is extended to allow for the wei ght of the components of the mechanism itself. The originator of these devices was George Carwardine, whose patents over t he period 1931-35 show the evolution of his ideas on this subject. A short biographical note is included as an appendix.