"Universal equation solver " - that was the name given to this clever device in the Encyclopedie of Diderot, which was published in Paris in 1751. The exhibit, created from the original drawing (patent 1133-37604123-A, registered 10/10/1993) allows the user to graph any 3rd degree polynomial, and, by doing so, to find the approximate solution of any algebraic equation with real coefficients of a degree not higher than 3. With the the same building principle is possible to construct the fixature n, a device to graph any polynomial with degree n. From the mathematical point of view , the way the machine works is simple, cleverly exploiting the similarity of proper right-angled triangles.