Willgodt T. Odhner invented his very successful “pinwheel” four-function calculator mechanism in Russia in 1874, and his invention was cloned by numerous companies, resulting in dozens of similar models that remained in wide use for almost a century. Numbers are dialed into the sliding levers on the top part of the machine, and are added to the register visible in the carriage at the bottom when the large crank is turned. Shifting the carriage sideways allows multiplication through a sequence of addition operations; the two small cranks zero the registers. The design includes ingenious error-preventing interlocks between all the controls: should the operator fail to return a crank to its resting position, the other controls are frozen until this is corrected. A bell indicates calculations in the negative. Used in Ballarat Institute of Advanced Education (B.I.A.E) Physics department.Black, mechanical calculating machine. Metal. Hand-operated, with three hand-cranks. 10x10 rotor with 13 digit result. Ser. No. 29-286781.5 Black symotape on base front: "PHYSICS". Maker's identification on top surface. Supplier's label (metal, silver & blue) on back: "STOTT & HOARE Pty. Ltd. 171 William St. Melbourne C1 M1991". Stamped on rear panel: "MADE IN SWEDEN". Cast lettering on underside: "M-602 07".calculating machine, pinwheel, calculator, scientific instruments, stott & hoare pty ltd, physics, odhner, ballarat institute of advanced education

This calculator is like a modern calculator style keypad with a traditional pinwheel calculator. In operation it is similar to other Facit machines. The design from the 1930s was produced without interruption with only slight modifications until the early 1970s.This one hasn't a serial number or Model Number so date is unknown but probably the 1940s - 1950s when the SEC were constructing the Kiewa Hydro Electric Scheme.Used by the SEC Office Staff when the SECV were constructing the Kiewa Hydro Electric SchemeBox shape with grey steel top and sides on a black base. Three thin strips of stainless steel embossed with numbers on the top and clear panels beside them. Front has 3 red and 10 black knobs with arrows on the red and numbers on the black. Sides have stainless steel pedals and winders. The machine is very heavy. See on-line "mechanical calculators.wordpress.com"'Facit' on the front.calculator, facit