The Keuffel & Esser 4012 Thacher Cylindrical Slide Rule Calculating Instrument is a vintage engineering tool originating from the United States. This cylindrical slide rule, designed by the renowned company Keuffel & Esser, offers a unique and precision method for solving complex calculations in engineering and mathematical applications. With its durable construction and intricate design, this slide rule is a valuable collectible for those interested in the history of engineering tools and mathematical instruments.
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