Abstract: An equipoising arm structure which can support relatively heavy objects, yet is compact in shape, and which can be counterbalanced by commercially available springs. The mechanism employs conventional parallelogram linkages for its lower and upper arms, with the lower arm being connected between a base bracket and a floating bracket, and the upper arm being connected between the floating bracket and a support bracket for the object. The upper arm includes a unique springing arrangement in which the ends of the springs attached to the brackets are connected beyond the conventional point of connections so as to maximize the lift of the springs when the upper arm is horizontally disposed. Means are provided for compensating for the non-linearity of such a springing arrangement over the range of angles of the upper arm that would otherwise normally occur.