A card circular calculator ‘McDermott’s Screw Propeller Computer’ manufactured by Taylor & Carpenter, Ithaca, N. Y. USA, and signed for the owner in ink ‘H Hall 1904. Paper instructions to the side. Condition good noting one corner torn on Surface ratio scale and a small rough hole on the speed scale. All in a scuffed faux leather folder
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Fletcher Wallis sells objects and books relating to the history of science, medicine and technology from his unit at Admiral Vernon Arcade Portobello Road. He publishes books through Vernier Press, including Antique Medicine Chests, and Corkscrew Patents from 1795. He has been dealing for thirty five years.