Abstract: An adjustable arm for controlling the horizontal and vertical position of an object mounted at one end of the arm comprises:means for rigidly mounting the end of the arm opposite the end at which the object is mounted;a plurality of interconnected links, a first group of the plurality of links controlling the horizontal position of the arm and the object; anda counterbalancing link among the plurality of links, the counterbalancing link being disposed intermediate the first group of links, the counterbalancing link serving to provide vertical movement of the plurality of links and the object and to counterbalance the weight of the object at the one end of the arm.