A Curta type I mechanical calculator, Contina Limited, Mauren, Liechtenstein, 1964 The circular top with cranked operating handle, clearing lever and moveable decimal markers within outer silver and black bordered numeral apertures with the former being the quotient dial and the latter being the product dial, the cylindrical body with knurled upper carriage rotating against a numbered position scale calibrated 1-11 over inscribed text CURTA and eight vertical setting register sliders each adjusting 1-9, the base with fixed knurled collar incorporating two further moveable decimal markers, the underside inscribed Type I, No. 56276, Made in Liechtenstein… by Contina AG Mauren, System Curt Herzstark, diameter 5.3mm (2.125ins approx.), in original black satin finish metal plastic sleeve case 12cm (4.75ins) high and complete with instruction leaflet, computing examples booklet, guarantee dated 27.7.64 and cardboard box. The Curta portable mechanical calculator was invented by Curt Herzstark in 1938 just before he was a prisoner in the Buchenwald concentration camp. During his incarceration he was allowed to continue working on the design presumably due to the future possible benefit of his Nazi captors. Following his liberation by American Troops Herzstark completed and perfected the design. The calculators were made in Liechtenstein by Contina AG Mauren and were widely considered the best portable calculators available until the development of the electronic calculator in the 1970s. Two models of Curta calculator were produced. The type I had eight digits of slides, a six-digit revolution counter and an eleven-digit result counter. The larger Type II was introduced in 1954, and featured eleven digits of slides, an eight-digit revolution counter, and a fifteen-digit result counter.