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

Plaque: ‘Hans W Egli/Ingenieur / Fabrikation von flechenmashinen [sic; ?] / Pat. O, Steiger / Zurich II / No 2566. Sole Agents for Australia / Peacock Bros./ Business Systems Company / 558 , 560, 562 Collins St., Melbourne / and at / Sydney, Adelaide, Perth’ Plaque: ‘Presented to . / Department of Information Science / Melbourne University / by the / Gas & Fuel Corporation of Victoria / This calculating machine was used by Engineers of the Metropolitan Gas Co and Gas & Fuel Corporation / from 1917 to 1970’