Model of an Optical Telegraph

Model of an optical telegraph on a foot. It consists of two poles above connected by an axis around which an arm rotates; the two ends of that arm are attached two narrow arms, one with a counterweight, the other without. The main arm is moved by a rope running over two discs on one side of the poles; the outer arms are moved with tackle running over a drum between the poles and secured on clamps against the poles. In the rectangular positions relative to the main arm, the outer arms can be locked with a spring. Scale 1:22 (scale on model).