A rare Abdank-Abakanowicz Intergraph, Swiss, circa 1911,
signed G. Coradi, Zurich, Switzerland, No 297 this high quality instrument was used to solved graphically differential equations, the polished blued steel instrument, in original fitted pine case, with a copy of the printed instructions and description by Henry Lossier, dated 1911 17.5in (44cm) wide