A Friden Model STW10 mechanical calculator. Motor driven “calculating machines” were developed and put in service by a number of companies before the advent of electronic computers at the start of the 1950s. The STW10, which measures 35 cm along the movable, 20-digit, upper carriage was first sold by the Friden company in 1949. It’s subsequent successor, the Model SRW, was marketed several years later and had the added ability to calculate square-roots of numbers.
At CRNL, the “calculating group” (so-called before the “computer group”) used the Friden STW10 as well as similar calculating machines made by Marchant and Hughes-Owens. It has not been confirmed that this particular unit was used at CRNL. The name plate on the side of the machine indicates that it was originally the property of the US Navy. A paper tag attached to the power cord indicates that it was counted in an inventory made in 1972.
