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A Simple Flat Stylus Adding Machine. This stylus slide adder was...
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This is a double-sided circular slide rule calculator consisting...
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Otis King Slide Rule Calculator Model 'K'. This is a cylindrical...
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Consett Iron Co Ltd Weight Calculator for Steelwork. Double sided...
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Fowler & Co. in Manchester made this pocket calculator. It was...
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This is a logarithmic cylindrical pocket slide rule with helical...
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This Planimeter is a Polar type integrating machine that was made...
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This Planimeter is a Polar type integrating machine that was made...
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This almost new Planimeter is a Polar type integrating machine...