Experimental compensation balance designed to accommodate Middle Temperature Error (MTE). The balance is of unknown origin but is reminiscent of Kullberg's flat-rim balance, with the bi-metallic element arranged in alternating triangular sections of brass and steel, the steel triangles with the bases on the inside of the rim and the brass on the outside. A similar design, but with these elements applied to a balance with conventional, vertical rims, was invented by Henri Robert in the 1820s and re-invented by the Genevan watchmaker Władysław Bandurski and, independently, by the American Charles Woerd in the 1870s. This balance probably dates from a similar period in the last quarter of the 19th century and would appear to be of English manufacture.