265,098. Dubois, W. A. Sept. 17, 1926. Balances.-A selfcompensating spiral spring is associated with a unimetallic balance a having separated sectors b which form a substantially complete rim, c and d being the slight airgaps. At two or more of the free extremities of the arcs compensating masses e are permanently secured to the balance. Nuts f form adjustable stops to limit the play of the bimetallic parts of the rim. Modifications are shown in which the rim is cut at various points, or three radial arms are used, or the compensating metal e is applied in different ways to the rim.